The EF Core tools version ‘3.1.2’ is older than that of the runtime ‘3.1.7’. Update the tools for the latest features and bug fixes

UPDATE
This turned out to be an issue with a lot of facets. Main problem was Visual Studio:
https://developercommunity.visualstudio.com/content/problem/438312/vs-2019-preview2-after-saving-edmx-code-is-not-gen.html

Please try

dotnet tool update --global dotnet-ef

and restart Visual Studio