MSCHAP RADIUS Authentication Issue

Hello,

I'm trying to get Observium to authenticate with my Windows radius server using MSCHAPv2.  I've followed the documentation and have managed to get it working with PAP, but any other auth types fail.  Using MSCHAPv1 gives a message of "A RADIUS error has occurred: No valid RADIUS responses received" on the Observium login screen and the radius server logs say the message it's receiving is malformed.  Trying MSCHAPv2 gives no error on the login screen but the logs on the radius server show an incorrect username or password error (I am definitely using the correct username and password).  Please could someone investigate?  Many thanks