Yeah, I know but is so painful there. It really support UDIMs only with Arnold texture node and baking with Arnold is still so much a puzzle. It needs low res to be never intersecting hi res surface
I tied it couple times but it never worked with UDIMs. Does it really? I once managed to get it working with some other naming convention but couldn't recollect now what it was? And I had other issues with Max RTT as usual; super slow , weird artifacts everywhere, etc so haven't tried to bake something in MAx for couple…