Steps to reproduce:

1. Open the linked Git Project
2. Navigate to Window > Rendering > Lighting
3. If there's no Lighting Settings Asset create one and assign it
4. Scroll down to the "Lightmap Packing" section and set it to "Custom"
5. Set "Packing Method" to "XAtlas"
6. Generate Lighting

Actual results: Editor processes start with the "Hold On" "LightingWindow.MouseUp" and takes ~20 minutes until the Generation appears in Background Processes, cancelling the also takes ~20 minutes
With the "Packing Method" set to "Unity" it takes ~1 minute until the pop up disappears and Generation can be cancelled, cancelling is almost immediate

Expected results: Users should be able to cancel Lighting Generation if the process takes too long and users shouldn't be locked in to a process for a long time, if this is expected cause of the new Packing Method there should be some sort of indications to the user why it's taking so long, not only that a process is ongoing for UI

Reproducible with versions: 6000.3.0b1

Can’t test with versions: 2022.3.66f1, 6000.0.56f1, 6000.1.16f1, 6000.2.0b4 (No XAtlas Feature)

Tested on (OS): Windows 11