If there is a visible envelope on a track, and you drag an item on another track from one side of it to a track on the other side (IOW passing over it) it deletes the envelope points, which shouldn't really happen. This isn't stopping over the envelope, just dragging an item from one track to another when there is a track with visible envelope between them. The way to avoid this is to not have the envelope visible, or rearrange the tracks to be adjacent first, but that should be unnecessary.
In the licecap I'm dragging the item to the destination track, points on other track are deleted, and then I undo it, so the points reappear.