Windows 10 WLAN prelogon not working

First time posting here, although I've found many helpful answers on the various StackExchange sites over time.

My current problem is that I cannot get WLAN prelogon to work on wireless laptops, no matter what I do. If the user logs on once using a wired connection, Windows will cache their credentials and let them log on after that with no problems, but if they haven't logged onto a particular laptop, or if the cached credentials expire, then the logon doesn't work.

I've set up the WLAN Prelogon registry key, and I've added the selected WLAN profile via a group policy. Domain controller certificates are, likewise, pushed down to the system via a group policy.

I've got a Windows 2012 R2 AD domain that all the laptops are members of. Wifi network is Ubiquiti UniFi using RADIUS back to the domain for wifi authentication. Laptops are a mix of Dell models, but most are running Windows 7 (I know) or Windows 10.

I've honestly been beating my head against this on and off for months and can't find the problem. I've searched for solutions but every one I find lists steps I've already taken. If anyone has suggestions on steps to take to isolate the cause of the problem, or if anyone has run into the same problem before, I'd appreciate any guidance.