No ActiveConfiguration on new project causes EFCore migration .deps.json does not exist error

**Visual Studio Version**: VS2019 16.8.3

**Summary**: I was asked by the EFCore team to post here since it seems it's related to the project-system. I created a brand new project, added EFCore to it with a simple blog.cs class, then tried to add migration and received the dllname.deps.json file not found:


@bricelam asked me to run some commands to get more details on the problem:


The only thing I did is create a new .Net 5 project, nothing else.

My project conf with my configuration manager details:


Reference to this case: https://github.com/dotnet/efcore/issues/23607

I also joined the .zip of the project. Please help, I haven't been able to run ef core commands from package manager console for like almost a year now.
[TestEFMigration.zip](https://github.com/dotnet/project-system/files/5668056/TestEFMigration.zip)