Rider unable to restore packages in .NET project?

Question

I'm trying to build a project which has been building fine for months, although now I've got a odd popup in Rider. I don't understand where its got the windows type path from, I'm on Linux.

  Microsoft.PackageDependencyResolution.targets(267, 5): [MSB4018] The "ResolvePackageAssets" task failed unexpectedly.
NuGet.Packaging.Core.PackagingException: Unable to find fallback package folder 'C:\Program Files (x86)\Microsoft Visual Studio\Shared\NuGetPackages'.
   at NuGet.Packaging.FallbackPackagePathResolver..ctor(String userPackageFolder, IEnumerable`1 fallbackPackageFolders)
   at Microsoft.NET.Build.Tasks.NuGetPackageResolver.CreateResolver(IEnumerable`1 packageFolders)
   at Microsoft.NET.Build.Tasks.NuGetPackageResolver.CreateResolver(LockFile lockFile)
   at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheWriter..ctor(ResolvePackageAssets task)
   at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader.CreateReaderFromDisk(ResolvePackageAssets task, Byte[] settingsHash)
   at Microsoft.NET.Build.Tasks.ResolvePackageAssets.CacheReader..ctor(ResolvePackageAssets task)
   at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ReadItemGroups()
   at Microsoft.NET.Build.Tasks.ResolvePackageAssets.ExecuteCore()
   at Microsoft.NET.Build.Tasks.TaskBase.Execute()
   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
   at Microsoft.Build.BackEnd.TaskBuilder.ExecuteInstantiatedTask(ITaskExecutionHost taskExecutionHost, TaskLoggingContext taskLoggingContext, TaskHost taskHost, ItemBucket bucket, TaskExecutionMode howToExecuteTask)

When I try dotnet build:

/usr/share/dotnet/sdk/6.0.101/NuGet.targets(130,5): error : Could not find a part of the path '/media/Storage/repos/Emulator/Emulator.Shared/obj/6300a645-3896-4d13-9cf3-ba21f3b6a6a9.tmp'. [/media/Storage/repos/Emulator/Emulator.sln]