Have to file as a South Carolina non-resident if my rental had a loss?

We live in Georgia and rent our lake house, which is in South Carolina.  On our federal taxes, the lake house lost money.  Turbo Tax is flagging that we need to file in South Carolina, but I read somewhere online (can't find it now) that you don't have to file in South Carolina unless your SC income exceeds a certain amount.  Does anybody know for sure how I can find out whether I have to file?  I call the South Carolina phone number but it says all agents are busy and hangs up.  I have an email out but I'm not confident they will get back to me.