I've been experiencing the same issue. I submitted my Federal return and waited for the state forms to be "ready".
The fix I found today was to delete your state entry (i.e. go to the State tab of your return. On the "Status of your state returns" page, delete the South Carolina entry by clicking the trash can icon.). Then add the state return back again for SC. All the info from the federal tax return will auto populate. It will allow you to pay for the SC state return and submit the return successfully. Hope that helps!!!
