Hello,
It’s definitly due to the new event data system after the update. I’ve tested before and after.
I’ve found a temporary solution, in the post object/relationship field you have to had the CPT “Events” AND “Series” (Or Serial, I’m not sure how it’s called in English).
That way they will finally appear.
The only thing, is the filtering won’t work, but the search will, so it’s not ideal, but at least they are selectable.
Hope it solves your issue as well.
