STP Warning in Unifi -- Delivery Optimization.

[chazzy2501]

I've been seeing STP warnings for a while now on my network but as everything was working, I've not been too concerned.  Well today I went chasing one and observed that the STP block was bouncing around 5 different sockets (wired Windows PCs) on the same switch.

 

I think I've twigged that the P2P updates for Windows update must be triggering the STP alerts. I do have delivery optimization enabled. 

 

Does this sound plausible? 

 

Also couldn't find an "edge port" option in unifi...