I recently added 5 Iris zigbee plugs with the built-in Z-Wave repeaters, and almost immediately started having Z-Wave issues. A couple of my switch devices disappeared. Bobby told me about the issues with the z-wave repeaters in those outlets, so I unpaired the z-wave side and all went back to normal. If you have them paired as Z-Wave repeaters it's worth a shot removing them to see if things get better.