I just reviewed the 1041 and it looks like this information is a new requirement for EFile in Tax Year 2018. The good news is there is a way to get the program to fill out the Preparer's Signature line for you on all your returns without typing it in. 

1. Open ProSeries. 
2. Go to the Tools menu then Options. 
3. Choose Firm/Preparer Information on the left side of the screen. 
4. Under the Preparer/Electronic Return Originator (ERO) information section check the box for Print name in signature area?

Now the program will fill out the Preparer's Signature block for you on all returns and clear the new error message in the 1041.