To get the PA non-resident withholding to show on the NRK-1, you have to enter it on the Schedule K-1 worksheet for each non-resident shareholder.  The spot is at the bottom of the box and is labeled "NRK-1 Line 6: estimated tax withheld for this shareholder"  The Schedule NW (even when it's working!) does not populate the K-1's.

In order to get my K-1's out I calculated on a spreadsheet the withholding, doubled checked it with the distribution checks I issued, entered it on K-1 worksheet, and mailed out the K-1's.  I also overrode the Schedule NW.  I haven't yet filed the PA 20 S hoping ProSeries will correct the error.  I have had 2 conversations with tech support people; both ending with, "Yes, I see the problem and will report it."  I'm worried that if they don't correct it PA will not accept an e-filing with all those overrides.