Invesco PA Muni Specified Private Activity Bond Dividend Affecting Refund

I received a 1099 from Fidelity for a non-retirement account which is 100% invested in the Invesco PA Tax Free Muni Fund. When I imported the information into TT my refund decreased by several hundred dollars. There is an amount shown in the 1099-DIV Line 12 for Specified Private Activity Bond Dividends which is for AMT purposes, however I am not subject to AMT. Is this a bug? Otherwise why would tax free dividends affect my refund? 

 

Adding Line 12 from the 1099-DIV also increased the nominal amount I now owe PA by a few dollars which again to me makes no sense.