Are you asking about (1) the input for 1120S, related to the reporting of the loss or (2) the input for 1040, related to the reporting of the K-1 items on the shareholder's return?

For (2), @sjrcpa has answered.  Line (9) Net section 1231 gain / loss has two lines.  You make the call.

For (1), what kind of activity was the sale for?   For example, if it was for a Form 8825 activity, check the non-passive box in the General Info on the 8825 input screen 21.

Note: The K-1 for 1120S has only one line 9.  For rental activities, the passive vs non-passive is reflected on the statement.