.net standard assemblies in .NET framework apps

See more:

C#

.NET-Standard

.NET4.7.2

Using Visual Studio 2019
Building console app solution

I have a solution with the following assemblies:

- ConsoleAppCore - console app targeting .Net Core 5.0
- ConsoleAppFrame - console app targeting .Net Framework 4.7.2
- Common - library assembly targeting .Net Standard 2.0

If I add a reference for Common to ConsoleAppCore, everything is okay.

If I add a reference for Common to ConsoleAppFrame, the namespace in the Common assembly won't resolve when I add the appropriate using statement.

Am I not understanding what .Net Standard is for? Is it more involved than what I'm assuming I should do?

(Notice I'm using .Net Framework 4.7.2 which is supposed to be "fully compatible" with .Net Standard 2.0.)

What I have tried:

I tried using the .Net Standard assembly in a .Net Framework app, and my life sucks as a result.