Hi TandDHall, we are FROG Members and will also be a vendor at the Rally doing Seminars on Holding Tank Care. I hope to meet everyone from the forum!
If you had sensors working properly and after you dump, they are not reading accurately, the best thing to do is completely feel the tanks and dump again, (several times if needed) to get any debris off of the sensors. Allowing the debris to dry on the tank sensors is where long-term problems can occur.
Dish soap is often recommended on forums, and I can agree that it could help, the problem with dish soap is that dish soap is a degreaser and the seals and valves need to be lubricated, not degreased. If you do use dish soap, make sure to rinse it out well after and do not use dish soap regularly. It can dry out the seals eventually if over-used, possibly causing the need for valve replacement.
I am by no means saying that it won't help, I am simply suggesting not to over-use dish soap in the tanks.