To Any Maryland Expert Preparer - 

A Maryland resident works out of state. The employer withholds Local tax (field 19 on the W-2).

However when Proseries calculates the credit for taxes paid on the 502CR, this amount is not captured when calculating the Local tax credit. (This all goes back to the Wynne Case I believe)

So my thinking is I need to manually override the fields and include a copy of the Locality's Local tax return

(as well as the non-resident State return) with the MD502 and mail the thing since trying to e-file a return with overrides does not work. That makes sense to anyone.