Post-midterm Trump's inability to act before a Democrat congress started turned him into a lame duck and all the plan trusting and hopeful anticipation boiled over into rage at nothing getting done. Combined with cancelling a chicken game of government shutdown just to have a shitty state of the union, and Mueller shit continue, it was too much for the alt-right.
So they've been against Trump for about a year, especially when he goes Neocon and wars in the middle east. The Iran stuff almost jumpstarted the IRL marches of 2017 that Charlottesville took all the wind out of the sails of. Remember, there was a lot of energy post-Spencer's rallies in A&M and Auburn, it seemed like the alt-right would be a national normal. Then the police just fucked them over, people died, and energy disappated when the TWP and sorts weren't dealt with, because people were trying to tell optics cucks to fuck off. This led to divisions between Anglin, TRS, and the Cantwell stuff, so now all the disparate nationalist white ringers are not talking to each other.
It's been a Neocon coup in the white house, and the Alt-Right is disorganized and dissolutioned. They aren't getting involved much in 2020. I think 2024 will revive them if Tucker Carlson or someone runs, but Trump left a sour taste of 'new boss same as the old boss'. The alt-right did NOT want another Dubya, wars in Iraq and sihtty tax cuts were running out replacement cuck. But that's what Trump has become, with the illusions he's doing something, anything.