As a newbie to this forum, with a 2020 1500 Classic I was surprised at how poorly the windshield defrost worked on my Ram. After having a 07 FJ since new, I was used to windshield defrost issues with the flat FJ windshield epically with freezing rain, or fog.
My Ram consistently has issues not clearing the frost directly infront of the drivers seat, it's almost as if there is something blocking the air from the defrost vents in the windshield, as there is a inverted triangle directly in from of my face, and the passengers, so I have to lean on the center console to see when we get freezing rain. I will try this full heat and AC on trick to see if this resolves my issues.
As far as comments on OP people not active in the community, remember there are lots of silent readers who gain knowledge from those of you who are regular posters and your wisdom and troubleshooting is greatly appreciated by many of those of us who don't actively post, So thank you!