Unable to upgrade storage pool to Qtier

[tamuct01]

I have a TVS-1282 running version 4.5.3.1652.
The NAS is populated with 8x 2TB HDDs and 4x 300GB SSDs in a single Storage Pool using Qtier. The SSDs were reaching the end of their estimated life, so I decided to replace them. The replacement SSDs are only 256GB, so I couldn't replace them one by one in the RAID group. I went through the process to evacuate the Qtier performance tier to the HDD tier and removed the SSD RAID group. I've inserted the replacement SSDs and when I go to Storage & Snapshots and click Qtier -> Upgrade to Qtier when I click Next nothing happens. When I go to the Storage Pool itself and click Manage and then Upgrade to Qtier it hangs with a spinning square and "Checking Requirements." If I leave it to finish eventually my session times out and nothing happens. Any assistance would be helpful.