@carrottspc I had a similar issue and seem to have found a solution that may work for some others. I have 4 APs 3 which are wired and 1 that requires a mesh connection. I disabled the mesh setting on the all APs except the non wired one and the one I want it to connect with.
Preferred affinity would be ideal and this might be a poor plan if intended AP ever goes offline I don’t believe it can failback to one of the others unless I catch the notification and manually re-enable the mesh feature.