If I import a clip into Kdenlive, split it, and reverse the clip to the left, the clip to the right will become invisible until I reopen the project. After re-opening, the clip to the left is gone, and the clip to the right is shoved about 10 minutes down the timeline for no apparent reason.
This is one of the many problems we had before the code refactoring. It is fixed in the latest versions. Please give the AppImage a try and let us know if you find any issue still.
The problem appears to be gone in the latest AppImage (20.12.2). Thanks for your concern and reply. Unless anyone else continues to notice this issue, I'll mark it as resolved.