I answered on the other post that you hopped on to. You really need to stick to one post instead of the leapfrogging that you are doing.
Where you able to e file the 2019 990 form? I also have a 990 to efile and a 990T to paper file. when I checked the box 990 only and selected e file, the system gave me a critical error message and would not e file (indicating there is also a 990T with information). when I check the box for 990 and 990T, i get an error message that the 990T cannot be e filed. I have not attempted to e file with the box checked for both 990 and 990T.
How did you resolve?