I’ve got two wired Ring Floodlight Cam Plus that I’ve put together into a single light group. While I can use the light group within the Ring app to manually turn on and off both Floodlight lights together, motion at either Floodlight does not activate the lights in the other grouped light. I’ve also turned on Motion Detection for both lights as well within the light group, but still not having any luck.
It sounds like you are grouping lights in the Ring app correctly. The group settings should allow you to automatically activate all the Smart Lights in a Group to turn on whenever one member of the Group detects motion.
As for Cameras, if these settings are not working in the group, try checking the linked devices feature out.
Please also check the Cameras in the Ring app to see if they have any motion scheduling or settings that might conflict with their lights turning on. I hope this helps!