KB4556799 has been accused of causing problems with many machines. I reset machines frequently primarily to maintain the peak of performance.
I also tested a bunch of video cards so I reset windows after testing cards. Many do not want to reset Windows, then again they do not even have a backup plan.
KB4556799 has not been an issue with a clean setup.
It is known that Windows 10 version 2004 has some problems with Mixed Reality. It also has problems with DISM and some other system components.
Windows 10 version 2004 is not as of yet on Windows Update. This suggests Microsoft wants to fix the known issues before rolling it out.
Microsoft has been keen to fix the update process. The update rollup that is currently in use is adequate. Feature updates can be added to the rollup just as easily. The installer simply needs to be able to check all of the components and install what is needed.
Problems for some uses using a LTE mobile internet solution have experienced connection problems. Again, reset Windows eliminates problems.