When adding a new track to the timeline, this removes existing groups from clips. For instance, place an a/v clip on a video track, then split audio to an audio track. Note that there's another bug: the split audio is not grouped to its video clip. So now group them both. Next, insert a new track between the video and audio track. The result is that the group is lost, audio and video clips are now ungrouped again. Reproducible: Always
To be more precise: unbreaking groups only happens when a track gets "inserted inside" a group, so that some clips will move with the track they're on. Groups not affected by a track insertion, will stay grouped. I would expect that all groups are kept intact, even if tracks will be inserted "in the middle" of them.
Fixed in git now, thanks
I have to say thank you!