Managed to get things working by removing "Called-Station-ID" from the condition/restriction on the NPS profile. Just realised that Meraki used a different value in "Called-Station-ID" rather than using the SSID name, it's using BSSID (I missed this part when I scanned through the document on configuring RADIUS on Meraki). If we need to maintain this condition/restriction on the NPS profile, it appears that we will have to list all the possible "Called-Station-ID" on the NPS profile. Considering we have 2 SSID's on each WAP, running over both 2.4GHz and 5GHz radios, we'll have to add 4 BSSID's for *each* Meraki WAP on the NPS profile. We'll need to deploy 11 WAP's, so 44 BSSID's. This will get untenable, and unscalable, very quickly.
Is there any other way that's more scalable, but still using RADIUS?