When you disassemble again, put a straight edge along the top of the ports where the leaks appear to stem from.
At this point it really sounds like the heads may be warped but seems so unlikely since that is something everyone would have noticed during head prep?
If the sealing surface is warped, those could be resurfaced without disassembling the heads.
It is more common to find that the exhaust side is warped and needs resurfacing.
I should also mention that there should be no pitting on the gasket surfaces and even if you don't see any, you shouldn't be able to catch a finger nail on any of the machined surfaces.
Shops are often leary to resurface any heads these days in fear of being accused of over cutting them and ruining them?
I have seen surfaces that were still pitted after resurfacing and the machining marks kind of disguised the pits.
It is strange to mention all of these things but this is a VERY unusual situation and something non imaginary is causing it.