Form 8936 is filling in box 4b incorrectly

I bout a Chevy Volt in August 2019, so i should get 7500*50%=3750 for my credit due to the IRS phase out for General Motors. TurboTax correctly detects the 7500 part, but it does not apply the 50% reduction. So, this results in my 1040 calculated a refund that is 3750 too high! 

 

FYI on the actual Form 8936 that I view when I print the return has line 4a correct as 7500, 4b incorrect as 100% (should be 50%), and 4c as 7500 (should be 3750).

 

Now, if in TurboTax I manually change the 7500 to 3750, my 1040 is correct with the proper refund amount, but my form  8936 is still wrong. In line 4a it says 3750 (should be 7500), 4b says 100% (should be 50%), and 4c says 3750 (technically correct, I suppose)

 

I spent a while on the phone with a very helpful support person, and she confirmed there's no way to fix this right now, and that I should print and file via mail, and in the meantime she would escalate the support ticket to some higher-ups.

 

I've read other posts in this forum where turbotax folks claim this form was fixed in lat Feb or early March. Well, it's the end of April, and it's definitely broken.