This is indeed strange. I’ve checked back with the team as I currently can’t access my own v18 setup. The issue doesn’t seem to be common, but a bug on your setup.
What you could try is resetting your OSMC skin settings completely. Accessing your device via SSH, navigate to /home/osmc/.kodi/userdata/addon_data/skin.osmc.v18alpha and delete the settings.xml. After rebooting your device and switching to the OSMC skin, you should navigate to Settings/Interface/Skin/- Configure skin…/Backup/Reset and click both Reset all menu items and Reset all skin settings.
This should reset the skin to a default state that should function without issues.
If there’s still an issue, come back to us and we’ll try to assist further.