GitHub Dependabot not finding all instances of package upgrades in .NET solution

Question

Dependabot will not detect all instances of a package reference upgrade in my project structure.

My 4 Test projects in the structure below all use XUnit. Dependabot has detected a package upgrade from 2.6.6 -> 2.7.0 and created a PR for the change. However it has only 2 of the Test project csproj files in the PR. It has not found the package reference upgrades in 2 of my csprojs. The projects are all referenced correctly from the solution file.

Filesystem/Project structure:

• /src/SolutionFile.sln
• /src/API1/API1.csproj
• /src/API1/API1.Tests.csproj
• /src/API2/API2.csproj
• /src/API2/API2.Tests.csproj
• /src/API3/API3.csproj
• /src/API3/API3.Tests.csproj
• /src/Common.csproj
• /src/Common.Tests.csproj

My Dependabot file is as follows:

- package-ecosystem: "nuget"
    directory: "/src"
    schedule:
      interval: "weekly"
    target-branch: "develop"

Any ideas how i can get Dependabot to detect all package upgrades for my solution?