Section 179 is only allowed if the rental rises to the level of a "Trade or Business".

ProSeries automatically assumes rentals DON'T rise to the level of a "Trade or Business", so it does not put the gain/loss of the rental on Line 11 of Form 4562.

I've done overrides on line 11, but I just found out there is a "depreciation options" worksheet that as a spot that you can enter the additional income/loss on line 3b of that worksheet.