@MMoss (I realize I erred in saying MR32 in my previous response, as it was actually MR34)
The earliest one I found was from 25.1 "Condition under investigation prevents DHCP offers from being sent over the air (MR34)" This was right at the beginning of my school year and teachers were freaking out. I was able to get with support and engineering so they could gather info while it was happening. That Known Issue dissappeared in 25.5 without showing up in the Bug Fix section. However, I stuck with a 24.x firmware until just recently. I could deal with the abysmal throughtput on 2.4GHz way more than having to reboot 104 WAPs over 3 different sites practically daily.
I recently had a couple random MR34 issues on 26.2, but I chalk that up to 'ghosts' in the firmware upgrade process. A couple randomly didn't come online properly, while a couple weren't allowing connections. For that I used the remove/reset/reassign trick.