I had the same problem last year when I did add a PTLink Mesh system . I could not set my Bridge on it. As I could keept my Apple airport, I used it just for the nuki. Now I have to remove it so I need the bridge to work on the UNIFI
Usually i would say, please contact customer support, but i‘m not sure if they can help at this point because your request is too specific.
Especially because there is no general problem with unifi. We have bridges and Smart Lock 3.0 Pros running in it, without problems. The settings you shared on the screen look fine too. Must be something different. Maybe around VLANs (just guessing).