Hi,
I had the same trouble as you and am currently using the PC version of TurboTax Premier. After setting up the Wisconsin Schedule OS, choose "View" from the drop-down menu in the top-left, then click "Forms". This will switch what you are looking at into the individual forms. From here, you can scroll down in the "Forms In My Return" section on the left and look for the 1NPR form
(Pg 3 & 4)
under the Wisconsin return section. You should be able to manually enter Line 41 of Wisconsin Schedule OS into 1NPR Line 56.
Since the data is not auto-populating, I am not sure if TurboTax is correctly checking any errors associated with the manual input, which could be a major setback. However, I hope this helps.
*EDIT* Apparently if you try to e-file it the way above, it does not let you go through with it because it becomes a manual input "error". So instead, I deleted the Wisconsin return (by selecting "File" on the menu in the top-left corner -> "Remove State Return") and then finished all the returns for the other states. I made sure to redo the Wisconsin state return as the last one. The 1NPR form auto-populated after completing the Schedule OS. I was able to e-file after this.
