Mediabay (Loop Browser and Sound Browser) in 10.0.15 doesn’t preserve any custom Result Column order after quitting.
This was not the case in version 10.0.10.
I’ve also trashed my preferences but that didn’t help.
Upon testing further I’ve realized that the Loop Browser and the Sound Browser windows don’t retain Result Columns order and size, even if you just close and re-open these windows. You do not even have to quit Cubase.
The Mediabay window loses Result Columns order but keeps the size.