Which Unifi AP are you using?
I have multiple Unifi AP (Outdoor/+, Mesh AC, Mesh Pro), which they are controlled thru Unifi controller. The switch are unifi running in conjunction with MX 64.
You might issue where the AP my be stuck due change of controller or location of where it was first adopted. Alot of this happeneds due to the Unifi default inform-set is set to http://unifi.8080, something like. Uusually i have to set the inform set to the specifuc WAN ip of the controller that is ip so the AP nows where to go to grab or be setup, etc.
You might want to reset the AP to default setting and re adopt.