MuseScore will not completely start

Version of MuseScore: 3.0.5 x86_64 AppImage
Operating system: Devuan 2 (based on Debian 9) XFCE window manager
Attempting to run MuseScore from the terminal, the "splash screen" appears, then the main window outline is drawn, and immediately closes. In the terminal window I have the following output:
Jack appears to be installed on this system, so we'll use it.
QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor EGL are enabled
QApplication: invalid style override passed, ignoring it.
WebEngineContext used before QtWebEngine::initialize() or OpenGL context creation failed.
QXcbIntegration: Cannot create platform OpenGL context, neither GLX nor EGL are enabled
Failed to create OpenGL context for format QSurfaceFormat(version 2.0, options QFlags(), depthBufferSize 24, redBufferSize -1, greenBufferSize -1, blueBufferSize -1, alphaBufferSize -1, stencilBufferSize 8, samples 0, swapBehavior QSurfaceFormat::SwapBehavior(DefaultSwapBehavior), swapInterval 1, profile QSurfaceFormat::OpenGLContextProfile(NoProfile))
[9830:9830:0100/000000.853946:ERROR:broker_posix.cc(41)] Invalid node channel message
/tmp/.mount_Y8K2WR/AppRun: line 28: 9802 Aborted "${APPDIR}/bin/mscore-portable" "$@"
Received signal 7 BUS_ADRERR 7ffb596ab3a0

Also the following line is added to /var/log/syslog:
[pulseaudio] main.c: User-configured server at {e5395edf3071b58547554d535cb77b4f}unix:/run/user/1000/pulse/native, refusing to start/autospawn.

Any suggestions? I've been running MuseScore 2 with no problems.

--- Additional information ---
After some further reading, I tried to start musescore 3 with an existing file, and that did start the application correctly. However, with no filename argument, it still closes immediately. At least, I can get into it now, but the issue isn't exactly fixed.