To reproduce:
1. Build and Run notification test project, located in the package on Device with Android 12
2. Try sending any kind of notifications, including the ones that should generate the pop up (Fancy channel)

Expected: notifications are visible in taskbar and produce popup
Actual: notifications arrive (visible in console), however, they do not appear in taskbar nor produce pop up

Reproduced with Android 12

Reproduced on devices:
Google Pixel 5 (OS: 12) Adreno 620 Snapdragon 765/765G Android 12 Developer Preview 3

Not reproduced on devices:
VLNQA00267 Samsung Galaxy S10+ (SM-G975F) Mali-G76 NOT FOUND Android 11
VLNQA00230 Oneplus OnePlus6T (ONEPLUS A6013) Adreno (TM) 630 Snapdragon 845 SDM845 Android 9
VLNQA00010, Samsung Galaxy S8 (SM-G950U), Android 7.0, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540

Note: Android 12 Developer preview 3 as the version used

Logcat log upon notification arriving:

05-05 21:07:59.208 933 3052 I sensors-hal: [ssc_utils]get_qmi_debug_flag:244, support_qmi_debug : false
05-05 21:07:59.338 1848 1848 D NotificationService: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284: granting content://settings/system/notification_sound
05-05 21:07:59.339 1848 1848 D NotificationService: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284: granting content://settings/system/notification_sound
05-05 21:07:59.340 1848 1848 D NotificationService: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284: granting content://settings/system/notification_sound
05-05 21:07:59.341 1848 1848 D NotificationService: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284: granting content://settings/system/notification_sound
05-05 21:07:59.342 1848 1848 D NotificationService: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284: granting content://settings/system/notification_sound
05-05 21:07:59.345 1848 1848 W NotificationHistory: Attempted to add notif for locked/gone/disabled user 0
05-05 21:07:59.361 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284
05-05 21:07:59.362 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|1287116400|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|2147483647|ranker_group|10284|ranker_group
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|1502713181|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|2030451125|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|36006562|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.unity3d.mobilenotificationtests|1388428093|null|10284
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No bubble up: not allowed to bubble: -1|android|26|null|1000
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|0|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-587929433|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|399563938|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|254253767|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.369 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-349699875|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|1290789534|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|1700002892|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-1230590103|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|924928582|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-1952447483|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|111891170|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-400817041|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|619451855|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|1469844288|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|147587764|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-983464597|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-1458772452|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|812940892|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.370 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|362777475|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gm|-1441916376|gig:-1156754354:^sq_ig_i_personal|10232
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No bubble up: not allowed to bubble: 0|android|43|com.android.wifi|1000
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.apps.docs|0|vaidasm@unity3d.com::SUMMARY::396f45a57ead24a4e3c0570ceb2461ac|10227
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.apps.docs|0|vaidasm@unity3d.com::a:CHIME_COMMENT:540e42e89ac95023|10227
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.apps.docs|0|vaidasm@unity3d.com::a:CHIME_ACCESS_REQUEST:33565345b9f2f56d|10227
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.gms|1000|a:NEW_OAUTH_GRANT_RENDERER:127:0:103731008044864711794|10195
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No alerting: filtered notification: 0|com.google.android.apps.wellbeing|12|null|10188
05-05 21:07:59.371 2364 2364 D InterruptionStateProvider: No bubble up: not allowed to bubble: -1|android|32|null|1000
05-05 21:07:59.422 4622 4678 D DeviceStateHelper: Audo mode: 0
05-05 21:07:59.424 4622 4678 D DeviceStateHelper: Audo mode: 0
05-05 21:07:59.913 933 1068 D CHRE : @ 16669