I have been having repeated issues with QGIS 2.18 print composer for OSX High Sierra. The composer seems to continuously stop working correctly, after inserting my map frame red guide lines will appear at random, these won't disappear when using view > clear guides. The composer then seems to lock up and I'm unable to select or move any items on the composer using the mouse, I'm instead forced to move items around by adjusting the x/y coordinates which is extremely inconvenient.
Has anyone else encountered such an issue? I have uninstalled and re-installed several times but to no avail.