Happened unexpectedly, only to one project so far. I tried on M+ but was returning the error. Still loads but does not save. So I tried opening and saving on windows laptop, to the same result.
Looks like it is corrupt.
What is the surest way to recover the work?
My idea is to save the 8 groups, scenes do not matter, and check the settings (which ones?).
Has anyone done this type of recovery before?
