Lots of people don't have productive passions. They were focused on being valuable to their family and community instead. What now for them?
Adaptation, classification, a change in how people define themselves?
You point out what I think would end up being a rough patch, but one worth going through.
More importantly, UBI doesn't prevent people who want jobs from getting jobs, so that seems a completely irrelevant thing to bring up anyway.
I get that UBI doesn't prevent people from getting jobs. I support it. It's just not a solution for people who's jobs have been automated away because lots of people were never looking for the freedom to accept a job that pays less the way UBI allows. It's like shortening Everest to improve mountain climbers' quality of life.