Found it ... It seems that these have defaulted to ticked rather than unticked - i guess an update took place this weekend?
Many thanks ! Not the easiest thing to find, now unticked - RR will now hopefully resume normal service. Nearly all the other tick-boxes are ticked so I suspect any new ones default to ticked if / when they are created. Alternatively it might have been gremlins tinkering when the Proboards staff were off for the weekend?