Problem with transposing instruments and double accidentals

I am editing a piece for clarinet that uses several double-sharp notes. When I open STAFF PROPERTIES, even without making any changes, the double sharps are destroyed when hitting OK. They turn into their enarmonic equivalent (G natural) and the score gets messy. This is not undoable, which is dangerous.

While writing this, I also found a workaround. It's possible to edit the staff properties when in CONCERT PITCH mode. This way, the transposed notation is preserved.