Same here under Linux. Sometimes it gets as far as a window with initial menu, but doesn't progress beyond that.
Don't know if this is helpful, an attempt to run from the command line outputs the following:
~ $ ~/.joplin/Joplin.AppImage
xdg-settings: invalid application name
Try 'xdg-settings --help' for more information.
[54572:0812/210241.307725:ERROR:sandbox_linux.cc(377)] InitializeSandbox() called with multiple threads in process gpu-process.