I don’t have a focusrite so I am guessing a bit here so your mileage may vary. This is just a pointer in a direction and it is possible to end up routing audio in weird places, though mostly using uninstall will work! I’ve also not used ReaStream so my solution went a different path.
OBS only sees Windows audio devices - not ASIO ones. You DAW is seeing the ASIO driver so sees the Focusrite input.
There are a few ways to bridge gap but VB-AUDIO Voicemeeter (VB-Audio VoiceMeeter) works on my setup once I read the manual and figured out what the ASIO vs Windows bit was doing and how to route the ins and outs.
Best suggestion I have for you I’m afraid. Hope you figure it out.