I found the problem... a grain of powder got under the platform of the electronic scale. I shook it out and it works 100% again. When I put it away, it was on it's side in a cardboard box. The powder grain probably slid under there when I put it on it's side.
I ordered a calibration weight for the thing... I'll doublecheck it's functionality before I use it from now on.
GGaskill, what I do with the PVC pipe cap is fill it up from the can, then pour it into the container on the scale. It just happens to be the perfect size for my charges. Using it to fill the container on the scale speeds things up considerably. I slow down when it is almost completely transferred and let the scale tell me how much to leave in the pipe cap... usually not more than a 10th ounce. When the scale was acting up, it told me I only poured 2 ounces onto the scale, but the cap holds about 3.7 ounces... I knew something was wrong immediately.
When I started using the PVC cap, I washed it out with dish detergent and left the soapy residue. Soap attracts moisture, so the soapy film eliminates static. After use for a while, the inside acquires a graphite film from the powder, also static eliminating.