composite joinery yet again

[vfrontiers]

I need someone to tell me I'm an idiot... please... I have gone thru everything I can think of and can't get two walls to join... They are both composites... the thicker one a DUPLICATE of the thinner and the CORE widened.

Why can't these clean up?

Every time I go back to composites, I get burned like this... I must be daft and missing something....

[Laszlo Nagy]

What happens if you make the Priority of the Plaster skin less (maybe 9 instead of 11) than the Priority of the Plywood (10)?

I am also curious of what would happen if you moved that Window in the horizontal Wall to the left somewhat? Does that influence anything?