After rereading your question and realizing that your compensation was high enough that there was likely no concern regarding a self-employed retirement deduction affecting the results, so I revised my original reply. Please ignore the original reply that you might have seen a reread my first reply. The problem is almost certainly TurboTax's simplistic approach to calculating the combination of PTC and the self-employed health insurance deduction which does not always produce the best result given that the IRS allows other methods of calculation that TurboTax simply does not implement.
If you expect the PTC to be zero (and that's the end result that you get), just enter the insurance premiums directly in the Profit & Loss from Business section without marking the box in the health insurance section that is used to indicate that you are self-employed and bought a Marketplace plan. That will avoid TurboTax trying to do the iterative calculation and failing to get it to converge, producing a suboptimal result.
