Visual Studio 2017 steps into the wrong NuGet package location

I have several C# console app projects referencing different versions of a NuGet package. One application references the 1.2.3 version of the package but VS (Visual Studio 2017) steps into the 1.2.3-CI-20200602-01 version of the package in a different solution folder during a debugging session.

How can I get VS to step into the current solution's packages/MyPackage.1.2.3/src folder?

Things I've tried:

• Searching for any references to the other solution.
• Removing the package from the solution and adding it again.
• Closing VS, deleting the package folder, restoring packages.
• Deleting the bin and obj folders, cleaning and rebuilding.
• Emptying the symbols cache under Options > Debugging > Symbols and restarting VS.
• Clearing all NuGet caches under Options > NuGet Package Manager > General.
• Deleting the contents of the %TEMP% folder.
• All of the above before rebooting and rebuilding.

I'm getting close to rewriting the app from scratch, but if anybody knows the location where VS is caching NuGet package references for debug sessions it'll be much appreciated!