So I rebooted multiple times and tried again. Tried in Firefox, opera and edge all from the same machine and everytime I did, same behaviour. I could see my click being registered in the browser (in developer tools), but no response would come from server.
I then tried from a different machine, Firefox on Linux and worked exactly as intended. Having trouble explaining that one...
Nothing assigned as disk 1, I guess when I built the array I started from disk 2.
One quirk I did find during this process, I thought the issue was I can't add 2 disks at once, so I removed 1 of the new disks from the array. When I clicked format(and finally worked when attempting from the new machine) it formated both the new disk in the array and the new disk NOT in the array, even though it wasnt part of the array
After then adding the second new disk to the array, unraid is now "rebuilding data" onto the 2nd new disk. Seems like a bug to me.