ID 520457 - Photoshop: Adding a new layer to 3 or more layer comps/frames opened from Flix then saving results in at least one panel stuck on "Loading" and one animated panel

Problem summary
Opening more than 2 panels in layer comps or in the timeline, adding a layer to them and saving results in at least one panel not updating stuck in "Loading" status and one animated panel in Flix. The issue does not reproduce if layers are not added but existing ones are only edited.
 
Customer reported version
Flix 6.4.1
 
Steps to reproduce
1) Go to Preferences > Third Party Apps > Photoshop and set the Panel Open Behaviour to "Open in Layer Comps" or "Open in Timeline"
2) Go to any sequence revision and open 4 panels in PS (the bug also reproduces with 3, but less consistently)
3) Add a new layer and update the 4 layer comps or frames to all include the new layer
4) Save in PS to update panels in Flix
 
Expected behaviour
The 4 panels are versioned up in Flix and all display the updated thumbnail
 
Actual behaviour
All 4 panels version up, but there is at least one panel stuck in "Loading" for which the thumbnail will not update, and one panel will incorrectly show as animated

 
Workaround
- The issue does not reproduce when updating less than 3 panels at a time
- Use the plugin actions instead of saving
 
Reproduced by support
This bug has been reproduced in:
6.4.1 - macOS 11 - Windows 10
 
Unable to reproduce bug in:
6.4.0 - macOS 11 - Windows 10
6.3.7 - macOS 11 - Windows 10
 
Earliest version tested
6.3.7 - This issue doesn't appear in this version and has regressed