Is the port on your switch this AP is plugged in to flapping or are the customer SMs dropping and re-registering to the AP? Your post seems to imply both things are happening maybe? If so, the two issues are unrelated.
Testing cables is simple and necessary. I don’t personally like the Cambium switches at all, but they do provide better diagnostic data than anything unifi switches will. The cambium switches do provide basic cable testing. How do you have these APs connected to your switch? Fiber SFP or copper? I’m guessing copper based on your post.