Have completed the challenge level at 100%. I have 604k buildings placed. Busy with a MAM for the shapes with crystals, build the first MAM. For the rest only the buildings to keep pushing through the operation levels and blueprint. I have a saved copy in which, if I change one small thing (tried several different changes, like adding an item, moving an item or removing the item) the whole screen goes blank. Dark blank. If you hover the mouse over different parts you know there is something there but you cannot see it.
I do not want to lose this save file. But I believe a bug fix is needed. Each time it happens I quickly close, because I do not wish to lose all my progress. Turned the graphics down to minimum, hoping that would help... but no difference. First picture: what I see when it happens, last picture where I am busy trying to fix the NOT (it is in the wrong place). 2nd and 3rd my stats.
I play on MacOS (MacBook Air M2).