My guess is you deleted the MDL soundfonts - best to try uninstalling then reinstalling the extension. Second guess is that you are trying to use a third-party template not designed for use with MDL - be sure to use the actual MDL templates.
And in the future, when asking for help using MuseScore, please use the Support forum.
Comments
Using MDL? Sample score? Steps to reproduce?
My guess is you deleted the MDL soundfonts - best to try uninstalling then reinstalling the extension. Second guess is that you are trying to use a third-party template not designed for use with MDL - be sure to use the actual MDL templates.
And in the future, when asking for help using MuseScore, please use the Support forum.