Looks like NAM 5.0 SP4 is turning out to be another bad release like SP3. I seem to find a bug on every upgrade!
If you use the PasswordFetchClass (com.novell.nidp.authentication.local.PasswordFetchClass), do NOT upgrade to NAM 5.0 SP4.
NAM 5.0 SP4 breaks this method and it breaks it in a way that it is not easy figure out (you get a 500 error from the IdP).
Support is aware, no idea when a fix will be available.
Matt