How do you see the waveform in Reaper?
go into REAPER: Options --> Preferences --> Peaks/Waveforms. There are a few appearance options in there to choose from. Check out: "sample level waveform view".
Can t see waveform in reaper?
It's likely that REAPER is trying to cache the reapeak files in a folder that doesn't exist, or is write protected. Check it out. Saving the project should save those files to the project folder, which should solve the problem for now.