Yes, it is not uncommon that the Premium Tax Credit in connection with self employment goes crazy, and can even change after you file the tax return (it recalculates things when you open the tax return, and the calculations may be in a different order than when you originally prepared the tax return).

However, you said the numbers did not change.  That is likely due to a ProSeries update (or possibly even just the re-ordering of the PTC/SEHI calculation).  Some number or calculation was changed, but the result of the change did not actually affect the numbers on the tax return.  So the program detects that something changed, but can't really find what the change was because the final numbers are the same.

The Self Employed Health Insurance deduction (Line 29 of Schedule 1) does NOT automatically flow to the proper line on the QBI section on the bottom of Schedule C (or wherever else the self employment income is from), so you need to manually enter it there.