Did you install avast after updating windows? Maybe you have to update windows first and then install avast. Use Windows defender or MSE until you update windows, and them install avast.
I don't know the architecture of avast, but since it's a brand new version, problably a massive windows update is in order. The last time I formatted my laptop, i've had to download almost a 1.5gb of updates. It took hours to download and install. Specially the .NetFramework ones...
But yes, the new avast is full of bugs. At least there are people that try to help