As you have seen, ProSeries is severely lacking in this regard, even to the point of negligence.  Everything must be done manually.

You need to manually calculate and input the allowable amount into the K-1 worksheet.

You need to manually create a Basis statement.

You need to manually attach a PDF of that statement to the return.

When Basis is restored, you need to manually create a second K-1 worksheet to enter the allowable carryover losses.