I'd double check the Cl level of the water coming directly out of a return jet with the unit on. Take a plastic container, put it in the pool directly in front of a return jet, and use that as a sample.

Also, if your pH is on the high side, cl effectivness is reduced which you'll detect by testing a low FC residual. I target between 7.4-7.8.

If the display is working, and no red lights are on, I'd agree that you SHOULD be producing Cl.

Have you done a full set of water samples? If you post your results, something could jump out.