This was beginning to annoy me so I’ve spent some time reinstalling to try and get to the route of the problem. I tried a fresh install and then reinstalled each of my add-ons and mods one by one rebooting after each. I got right to the end without a problem, rebooted and had the problem. So I tried another fresh install and I think I’ve finally figured out how to stop it happening but not what the cause is. I have two profiles on the Pi. If the login screen is enabled the menu items and menu text are missing after a reboot and login. If the login screen is disabled then they appear as they should. I’ve tried this with a backup from before I wiped and exactly the same happens.
I think it must be something with OSMC though as I have a Nexus 7 with exactly the same addons and a login screen with two profiles and it works perfectly.
Log file with debug logging enabled is here