Well I can report that everything ran smoothly with SSELODGen with no seasons mods and it installed smoothly with Vortex.
DynDOLOD also ran very smoothly but Vortex again failed to install the Output zip with the following errors.
I have also found that Vortex has been unusually unstable this evening, crashing whilst trying to deploy mods, notification messages not clearing after they're resolved, e.g. for managing conflict rules, and flashing during some operations. So I do feel that Vortex itself is part of my problem but I obviously can't back that up with anything factual. Just leaving it here in case it matches with any other reported user expereinces with the current version.