To get them to work, you must do the following:
Goto "Manage Bottles" -> "Advanced" tab -> Select your FL Studio bottle -> "Browse C:"
Goto the folder "windows" -> open "system.ini" with your favourite text editor ( notepad, gedit )
Add the following line at the bottom of the file (without the quotes):
"msacm.vorbis=vorbis.acm"
Save.
Now the "missing" samples should work.