I had an issue and I solved it, and I figured I’d document it here in case anyone else runs into it. For some reason, after installing mrtrix3 through miniconda on Ubuntu 18.04, mrview didn’t work. It gave a linking error, citing that it could not find or load the Qt platform package “xcb” in “”. The “” tipped me off that it was failing to find it at all.
After scrubbing around the internet, what worked was exporting the Qt5 plugins path, as per the post here. So, add to your preferred config file (e.g., ~/.bashrc):
export QT_PLUGIN_PATH=<qt base path>/plugins
where you should sub in <qt base path> with the relevant plugins path. You can use dpkg with the --list-files argument to hunt down where qt5 can be found.