I just figured out that it's the time period 7/01/2019 - 09/30/2019 that GM vehicles aren't getting the 50% phaseout. If you enter a date in 4/01/2019 - 06/30/2019 then you get 50%.
You could enter 6/30/2019 and get the correct result on your 8936 and only be off on the date by a month+ which the IRS isn't going to care about <;-)
This will be fixed in the next TT 1040 update.
