The IRS believes that you should have a 1095-A from the marketplace and a form 8962 in your return ... until you deal with this issue the return will be on hold. So did you call the ACA and ask if you are on any ins policies ? https://www.healthcare.gov/get-answers/
Is it possible that you were on someone else's policy like a parent's for any part of the tax year ? If you were under the age of 27 that could be the issue ... so ask them for a copy of the form and allocate none of the credit to your return if they took 100% of the credit on their return.
