In the PDF attachment window you need to be sure to choose the 1116 as the "type", you have to scroll UP in that drop down list to find 1116. 

If youve got the right type chosen, try removing it, save/exit and  reopen the return and reattach it.

Nope... did not clear the error.  The error is showing on the EF Info Wks.  When I review the return, I get the instruction to attach the PDF file... even though it already attached.  The attachment is NOT showing on the attached Electronic (PDF) list on the EF Info Wks.

remove the attachment, save/exit then come back and try attaching again.

The solution works for an original return.

I can not get the solution to work for an amended return

Other suggestions?

Yea, amended returns dont seem to be very fond of attachments when Efiling....you may be stuck paper filing that one  😞