I had a similar problem with Visual Studio 2022 , I tried all the abobe solutions like downloading MSTest Package but nothing worked! , So turns out if you are using two different Testing frameworks NUnit and Microsoft.VisualStudio.Test , they both have different way of initialising Test host and the one you define in your global Usings.cs instruct visual studio which one to use , so if you use one and all the test are configured to use the other adapters code , it wil lnever work . just fix the usings.cs and update the using in individual test file.

global using NUnit.Framework;