I've been fighting for the better part of the day trying to get this working.

RBGrooveA-52HPn AP 192.168.10.9
RBGrooveA-52HPn Client 1 192.168.10.8
RBGrooveA-52HPn Client 2 192.168.10.10

AP and Client1 have been functioning fine for 2 years. Today i tried to add Client2. It never would work. I decided to update Client1 and AP to the latest version of RouterOS and that's when i realized Client2 was configured (sort of correct) and it Registered and was working as expected. However Client1 never would reconnect. Once i disconnected Client2, Client1 came back up.

I feel like it's a license issue, but they all should have OS L 4 licenses. I'm also using 802.11 protocol as it was the best for VOIP.

I've got no idea where to go from here.

What is the wireless-mode of the AP.
You must set to AP-Bridge.
Your behaviour seems to be a "Bridge" mode

Excellent Observation! Thanks. I'll try it again in the morning. You are correct, it is in Bridge, rather than AP Bridge.