When creating a composite take from lanes, I sometimes use “alt-click” to create a Composite split point, and other times I “click and drag” to create two split points around the selected region.
These two approaches behave differently under GROUP EDITING tracks. “Alt-click” will apply the split to all grouped tracks, but “click and drag” only applies the split to the selected track. This immediately breaks the synchronization between the grouped tracks.
I suggest applying the splits to all group-edited tracks, regardless of which method is used to split for Comp’ing.