I just tried renaming a .dng file the way I do so often in rawtherapee, but it refused to change its name. It just kept showing the old name.
Turns out I didn’t have write permissions to this file, so there was a logic explanation. Giving correct permissions solved the problem of course.
Maybe RawTherapee should tell me why it fails?
PS: This was observed with R.T. 4.2.1234 on Windows 10, 64-bit.