LumenRT file scene corruption - Will not open

Every time a try to export a decent size 3d file to LumenRT I get a "corrupted file error with a possibility of not enough disk space" I have 164GB of room on C:. I tried to export a couple of cubes and that worked fine. I have tried this across a few versions... Help ORD Connect Edition 2020 Release 2 Update 8 10.08.01