File Open/Save As dialogs are blank

Using the suggested fix for empty file save as dialog on Linux (i.e. executing "export QT_NO_GLIB=1" and then mscore) results in the save as dialog being correctly populated. However, if I try to save as either Lilypond or MusicXML format, the Save button changes colour when clicked, but the dialog doesn't close, and trying to dismiss it using either the Cancel button or the X in the titlebar does nothing. What happens is that after a few seconds, I get a msgbox telling me that the dialog is not responding, and offering the options of Force Quit or Wait. Wait leaves the dialog sitting on top of the Mscore window, and Force Quit terminates the whole Mscore application, not just the dialog.