Tab tree not in sync with tab bar when moving tab to the rightmost position (seems buggy in general)

Dragging a tab in the Chrome tab bar all the way to the right is not synced to the tab tree. The tab jumps back to its original position after a few seconds.

Starting point:

Moving tab in tab bar:

Immediate result in tab bar:

Immediate result in tree: Tab in wrong position (end-1)

Automatically moved back in Tab bar after a few seconds:

You can even lose tabs in the tree completely by moving them to the right end and back (keep mouse button pressed).

The latter might be a UI problem. Closing Sidewise and reopening it fixes the missing tab problem.