It's not mentioned in the release notes, so I don't know if that's an oversight.. but is the R750 supported by the vRIoT Controller?
For reference: vSZ: 18.104.22.168.302 vRIoT: 22.214.171.124.21 R750: 126.96.36.199.373
Given that it's the flagship AP and is IoT ready, you'd hope so.. but I'm having issues with them ('IoT Radio not detected', 'Gateway IoT firmware mismatch' etc.) and wonder if it's an 'is it even supported' issue.
vSZ was upgraded to 188.8.131.52.699 but the problem persists. It might be that as per the tech note you referenced, the hot upgrade might not have been applied. The vSZ in this case, is hosted by a third-party provider, so I can't be sure.
The APs are now at v184.108.40.206.5010. The tech note says the APs should be moved to the 5.2 zone AFTER the hot upgrade.. will this now cause issues if the hot upgrade hasn't been applied. I'm assuming the APs should be at 220.127.116.11.5030? (although the reference links in that patch don't mention IoT, or the R750)