FLStudio doesn't decompress the wave files when you first install the program?
After some research the IL website explains that: "Many .WAV files included with FLStudio are .OGG encoded .WAV files. These files require the Vorbis ACM CODEC ...
FLStudio installation folder. e.g. CD C:\Program Files (x86)\Image-Line\FLStudio 21. Then enter: All projects in a folder (including sub-folders) using a complete path - FL.exe /R /Emp3 /F"c:\src\", where c: is the target ...