I had a similar issue. Turned out the drain line from the dishwasher to the disposal had fallen down(still connected though). The hose needs to arch way up above where it attaches to the disposal. This may not have been your problem and it’s been over a year since your original post but for anyone else that comes to this thread take a look at the drain line.
Don’t chemically mess with a gray water drain!
It is kind of like a septic system and if you kill things eating the little bits of solids it will not last as long!
Soap scum is a solid in this case if you kill the bacteria it will plug up faster.
I could take the other side and say you should dump a caustic every now and then to turn the scum into less ...