Hey, thanks for the swift response.
looks like the naming change happened sometime earlier and I only noticed now.
The materials default on a new file too, but I think that’s a limitation of Revit LT FBX Export function - Autodesk stripped materials out of it.
I’ve resolved the issue by:
-Getting an old backup version and loading my new FBX into it - everything came in fine without any losses.
-In my newest TM file, deleting everything except for my latest changes, saving
-Opening up the backup and merging in the purged new file
Lesson learned - always keep backups