For some reason I keep finding these "SWG not working" threads because I started one myself a couple times. Turns out cell works fine, pool owner needed a reset. If my chlorine slips below the target in poolmath, I get organics eating up my chlorine and the SWG doesn't keep up. And, knowing I can go up to shock levels and safely use the pool lets me error on the side of extra chlorine, not less.
Since I've learned my lesson, and keep my levels between 7-10, I've not had ANY cell-working thoughts at all. Don't see bubbles, but I'm confident I won't get any algae blooms as I did in the past. if chlorine drops due to excessive rain dilution or swimmer load, I just boost with liquid bleach, and let the SWG take over MAINTAINING my levels, not creating my levels.
Much happier since I learned my lesson. As a side note, my PB was little help, outsourced all info/training to a third party pool servicing company who just wanted to keep throwing chemicals in the pool, like the pool stores suggest.