I also get that bug, though that's in a transferred-from-43.05 save. I'm not sure if that's because I'm telling my dwarves to recover artifacts from the same civ they belong to, even if it's a ruined site. I was hoping to use my old, abandoned forts as lootable caches of artifacts. Whether or not "won't do artifact recovery on own civ's site, even if the site is a ruin" is a bug or not, I'm unsure.
Speaking of migrating a save, I know that I can't make any new pedestals or display cases due to that being limited by worldgen, and likewise I won't get any through trade. Is it possible to get an artifact pedestal (moody dwarves occasionally making things they normally can't like bows, various clothes, etc.), or some other goofy workaround? Maybe a DFhack script that forcibly creates them, hmm. I think I'll be able to designate a museum around artifacts that can be built? It'd be nice to be able to cheat the limitations of this kind of thing, but I'm not expecting that'll be possible.
Either way, the idea of "priming" a region for the ultimately desired embark comes to mind as something I'd like to do. A fort for vampire/necromancy spreading, facilitated by an adventurer, and another fort for artifact generation, then finally the fort actually desired in its proper embark, for the contents and citizens of the previous forts to migrate to or be raided by.