You could try to toggle the switch multiple times to get rid of dirt or oxidation on the contacts. But since it’s quite a new camera it’s more likely the switch is broken. Too bad

Bugger no luck... looks like it's off for repair

Welcome to the forum. That sounds like an issue for which you might want to have your local camera store / repair shop take a look at it and make sure there is not any mechanical troubles happening in the switch. It seems strange the switch will let you choose settings on either side of those two, but not let you choose those two settings.

The usual recommendation is to completely initialize all the settings and see if that fixes it.

Yep I've got it in single image mode it occurs there