open ground question
You have what is called a multiwire branch circuit with shared neutral. If the cable entering the circuit breaker panel that has the red,black and white wire but no equipment ground wire (bare) then that is your problem.
The only other possibility would be if the wires are in metal conduit which could act as your ground.
Somewhere on the circuit is a junction box (hopefully accessible) where they split the mwbc into two 120 volt branch circuits. In that junction box is where the ground is open because there wasn't a ground wire in the red,black and white cable to continue the circuit back to the breaker panel.
" One nice thing about the NEC articles ... you have lots of choices"