I believe it may be related to the current versions of VS2019 which when creating a new Winform application do not allow you to target 4.8 framework and instead targets core 5.0 which then causes problems.
I'm noticed a problem and went and manually corrected the project file to target net48 and reinstalled and things started to appear as expected. An older project which was targetting the net 4.x framework was working fine during this time so didnt notice it immediately.