Thanks for the prompt response!
I’ve tried the left-handed setting, but that isn’t making a difference in terms of having the native Z-up models display correctly in Unreal. Furthermore, using the left-handed setting mirrors part of the geometry, so I assume the right-handed setting is the one to use on that front.
When it comes to FBX, I understand why you might be asking that question — FBX is notoriously inconsistent with coordinate systems. But again, I’m testing two FBX files exported from Max, and the issue seems to be how his plugin interprets their up vector declaration, not the FBX format itself.
Thanks for looking into the files, looking forward to knowing how to tackle this one 