RUI File Error - Toolbar corrupted after closing Rhino and weird "Macro 02 - Copy 00" tooltip texts

I’ve got a RUI file with toolbars and icons that is Rhino 6 seems to corrupt.
The first time I incorporate it into Rhino 6 it does work. Then when I close and reopen Rhino it looks like the software is corrupting the rui file. It shows a “RUI File Error” message saying that there is an error loading the toolbar file. I can force it to open the rui file again by dragging and dropping into Rhino, but the error persists each time I open Rhino again.
There’s one more thing, the buttons in the corrupted toolbar start showing weird texts when hovering. Those buttons that do not have a Tooltip text for the “Right mouse button” get a new text in the form of “Macro 02 - Copy 00”. This text is different for each button and seems to increase in time with more “Copy 00” substrings at the end.