Thanks for the screenshot. Your setup does indeed look correct.
Sometimes, such issues can occur when certain C# files are not properly (re-)built, and the engine thinks they are at a different location.
Can you try both going to MSBuild and pressing 'Clean Build', and if that still does not work, manually deleting the folder: C:/Users/Ian/Documents/GitHub/liminalita/.godot/mono
This 'mono' folder is where the compiled C# files are put when they are built, so if stuff goes wrong, deleting that often helps.
If the problem persists, would you please also send me the contents of the .csproj and .sln files inside your project folder?
Thanks for the patience, by the way, I hope together we're getting to the root of the problem.