My wife was just re-assessed for this exact issue. In my opinion this is a massive miss on Intuit's part and I no longer have confidence in using turbotax to file my taxes as I have done for many years now. I will be looking at other options going forward.
I've confirmed this is still a problem with the 2024 Tax software. To fix I found further up on form ON479-A in question #2 there is an option to check "One or more supporting persons for all eligible child" and "Was supporting person your spouse?", and by checking these off it correctly calculates the tax credit.
I will be filling a claim with Intuit.
