Great work, just one problem I had a structure for my project with a LIB solution folder and I place all my RCL there, it wasn't until I moved the RCL to the solution itself and deleted the solution folder that the extension worked and I could see the RCL classes.
Same issue observed here. I had client blazor projects within a solution folder, and had to move them to the root in order for the css classes to get picked up.
Great work, just one problem I had a structure for my project with a LIB solution folder and I place all my RCL there, it wasn't until I moved the RCL to the solution itself and deleted the solution folder that the extension worked and I could see the RCL classes.