Make sure you have BOTH of these:
.NET Framework Runtime 4.7.2 or above: dotnet.microsoft.com/download
.NET Core Runtime 2.1 or above: dotnet.microsoft.com/download
This something I did at the beginning to try and fox the problem. However even after restarting, uninstalling and reinstalling, I am still faced with the same issue. I didnt have this issue before, but only since the update
Might be something blocking the access, Did you make sure to run the trainer as admin? and see if you can download other .NET essentials, see if that works.