If I simulate colored paper for my canvas background I cannot export transparent PNGs anymore. This worked before just fine and I always used this technique to be able to work with white surfaces on a "invisible" colored background. When I link the Ai into Photoshop it ignores the background as it certainly should.

The weirdest part about it is, that the PNG always has white background (custom background is off) in the export window despite my colored paper being white at all! As soon as I deactivate colored paper simulation, the PNG can be exported transparent again.

I'm a pro, so don't tell me about any export mistake. This worked totally fine before and now it doesn't. So please just fix it and don't Adobe-talk me into "it's your fault after all - we can't do sh**".