There is no need to attach the 1095-C for Federal.

That IRS rejection code says that the 8962 is NOT part of the tax return.  So for some reason, your software seems to not be including it.  That is why I asked if there was any Advance credit or if there was any credit at all.  Or if you are allocating 0% to the taxpayer.

So does the 8962 actually show anything on lines 24-29?