MDL Extension playback not working

I've been using the MuseScore MDL drumline extension for years now, and it has been great. Recently though, the whole program started to crash mid-session nearly every time I used it, so I uninstalled the program with the hope that re-installing would fix the problem. I then realized that version 4 had been released so I installed that only to find out that the MDL extension isn't compatible with version 4 yet. I then re-installed version 3, but ever since I did that the audio playback is no longer working for the MDL extension. Playback for the rest of the instruments in the program is fine- it's only the MDL extension that doesn't work. I've tried everything I know to try and have searched all over for a solution but I can't find one. It's really important to me to resolve this issue because I'm an instructor and I use this software heavily for my students. Thanks in advance to anyone who can help me out.