This worked for us:

We entered the Form 1116, Line 2 "Expenses definitely related" on Line 5, "Losses from foreign sources", instead.  The Line 6 totals remain the same.  To cover ourselves, we add the following note to both Line 2 and Line 5 and tick the box, "Print this note as part of the tax return for filing":

These are definitely related expenses that normally are entered on line 2. Trouble is, there is a ProSeries tax software glitch associated with the line 2 required statement that prevents efiling when an amount is entered on line 2.  Therefore the expenses are entered on line 5 as a workaround to permit efiling.

We hope this is helpful, and we hope ProSeries is able to sort out this issue with the IRS soon and fix it in the software.