As I understand it the U1 camera doesn’t work in Fluidd. The K2 Plus suffers from the same issue. DnG Crafts came up with a work around for the K2, it may also work on the U1. I can’t say if this will work or not as I don’t have a U1 to test it on. Maybe SM came look at the code and implement it.
Hopefully the dev team will get it fixed. They’re aware of the problem and have promised to get it working.