I found the answer to this in another question. That is to download the Improved Closefaced Helmets __ WACCF from kryptopyr's Patch Hub Miscellaneous files. It is newer than what is in the main installer.
My problem is solved. After hours of searching, head scratching and trying 4 different versions of MO including v1.2.4 (which looks interesting but is not quit ready for primetime). Turns out it wasn't Archive Invalidation. The problem was an incompatability with 2 mods, Roberts Male Body with Fallout New Vegas Redesigned 2. Roberts Male Body Nexus page descibes what I was seeing, namely black bars on the body as archive invalidation not working. But.... Roberts uses a custom nif for upperbody.nif, which in turn uses a custom upperbodymale.dds. The body parts are laid out in a different pattern within the dds file. Fallout New Vegas Redesigned 2 uses the vanilla nif and dds layout. So when installing Roberts before FNVR2 MO/FNV uses Roberts' upperbody.nif and FNVR2's upperbodymale.dds resulting in what looks the same as Archive Invalidation. Simply hiding FNVR2's upperbodymale*.dds files fixes this. Hope this helps someone else who might be fighting the same problem. Thanks very much for your assistance.
