I was performing a brand new clean install (no settings changes or other addons); it seems that Better Dynamic Snow has been updated recently (22 July 2022 to 3.5.0) resulting in the following error during DynDOLODx64 generation. (The issue did not show up in LOOT, or while frametesting before generating LODs unfortunately ).
Upon rolling back BDS to 3.4.0, DynDOLOD didn't fall the first hurdle and completed successfully .
Anyways, I thought that might be useful for folks to know. (I hope I've posted this in the right place, sorry if it isn't )