Reproduction steps:
1. Open project “Repro_latest.zip”
2. Select the “AnimSyncMarker.asset” in the Project window
3. In the Inspector window, right-click on the timeline and click on "Add Marker"

Expected result: the marker info editor UI pops up
Actual result: the marker info editor UI does not pop up

Reproducible with: 2022.2.0a16, 2022.3.0f1, 2023.1.0b19, 2023.2.0a17
Not reproducible with: 2021.3.26f1, 2022.1.24f1
Couldn’t test with: 2022.2.0a1 - 2022.2.0a15 (due to compiler errors and AnimSyncMarker.asset not opening)

Reproducible on: macOS Ventura 13.2.1 (Intel), Windows 10 (by the reporter)

Note: “SyncMarkerTimeline.cs” line 468 causes the UI to close