If you had South Carolina gross income greater than the federal personal exemption amount ($4000), then you are required to file a SC tax return.
From the South Carolina Department of Revenue website (2015 SC1040 INDIVIDUAL INCOME TAX FORM & INSTRUCTIONS):
If you are a nonresident or part-year resident whose South Carolina gross income is greater than the federal personal exemption amount, you must file a South Carolina income tax return.
You may not owe SC tax because of the net loss, but the state requires a tax return if your gross rental income is greater than $4000.
Was this also true for a 2018 Return in South Carolina?
I know that I do need to schedule a SC nonresident return for my rental property. However, when it is asking for SC rents, royalties, and K-1 income, do I put zero (which is my net income according to my federal return after expenses) or do I put the gross rental income (without subtracting expenses)?
I am specifically referring to line 11 on SC Form Schedule NR.
Edited to add that the instructions for Line 11 say: “Enter in Column B the income or loss from property located in SC…”
You would enter $0 into this space, the instructions say to enter income or loss and you had no income. Line 48 on the form, for South Carolina taxable income, instructs you that "if less than zero, enter zero".