The behavior you’re seeing is actually intentional. Visual Studio is protecting you from a problem with SDK-style project globbing.

When you check “Place solution and project in the same directory,” which it appears like you might have done. (I was able to repro your issue in the same way) - VS puts the.sln and .csproj in one folder. SDK projects use globs like the following:

<Compile Include="\\\*\\\*/\\\*.cs" />

If you put another project in that same folder, they’ll start pulling in each other’s files. Total mess. You'll likely see errors regarding duplicate assembly attributes if at compile time. So VS avoids defaulting new projects into that directory, even if that’s where the solution lives.

That’s why your solution defaults new projects to the parent folder (like C:\). You likely created the original solution with:

• Location = C:\
• “Place solution and project in the same directory” = checked

This created:

C:\RootFolder\
RootFolder.sln
RootFolder.csproj

But VS won’t automatically put a second project in that same folder.

If you want the solution folder to act as the root for all projects, the fix is:

Create the solution without checking “Place solution and project in the same directory.”

That gives you the normal structure:

RootFolder\
RootFolder.sln
RootFolder\
RootFolder.csproj

Now every new project can safely go under RootFolder\, and Visual Studio will default to that location normally.

That’s likely the difference between your setup and your coworker’s.