Hello Volnaiskra, Yes, Yves solved the issue (back in july 2022, so the fix should be in the Last stable release).
As far as I remember it was a bug in the editor that was not causing project corruption.
And I didnt encountered this bug since the last build.
Thanks for replying. Very relieved to hear it didn't cause corruption! I've been working with the same qualifiers for a few more hours, and I haven't seen the error again. I'm using 294.14, so I guess I just stumbled upon a rare not-yet-squashed version of the bug. But if it's just an editor glitch, I'm not too worried.