I have the Morph with piano overlay connected to the system which also has a Lightpad Block (x2) and Blocks keyboard. When I open Reaper, it gives me an error - - “The following MIDI inputs could not be opened: Sensel Morph” and the Morph does NOTHING in Reaper. It works fine in Kontakt, but if it won’t work in Reaper then I’ve wasted money on this. I looked on the Sensel site and it seems like I’m either missing it or they just don’t have any content related to Reaper - plenty on Ableton, but obviously I’m not going to switch DAWs for the one piece of hardware that doesn’t work properly.
Windows or Mac? How are you connecting the Morph?
Here’s a quick video showing this working fine in Mac. The only real difference for Windows is that Windows will only let one application use a class-compliant MIDI device at a time, so make sure all other MIDI apps are closed.