Some values (not properly handled by do_versions?) could cause 'rna_backup_restore()' to throw an error resulting in the whole preview generation not being saved to the .blend file. I've checked folowwing demo files: - race_spaceship.blend - wasp_bot.blend Here the offending seetings were: - `UnitSettings` (`length_unit`, ...) - `FFmpegSettings` (`ffmpeg_preset`, ...) For now, these are now excluded in `exclude_props` Reviewers: brecht Differential Revision: https://developer.blender.org/D5255