WPA2 Enterprise [PEAP] on IOS 12 -> "invalid password"

I'm using Apple Configurator 2 to deploy our CA certificate and a WPA2 Enterprise WiFi profile to an iPad.

The WiFi Profile is set to

WPA2 Enterprise

PEAP

the appropriate credentials

and under "Trust", the CA is checked

However, when i deploy the profile and try to connect to the given WiFi, I always get a popup saying the password would be invalid.

On the side of the RADIUS server there is no activity at all, so it appears, that the negotiation process doesn't even get that far.

I'm not sure, what the issue here is, since it's is working perfectly with Macbook Pro, Windows 10 machines and any Android devices I came across so far, after importing the CA to each device.

Anyone facing the same issues?