Watch the oven. Too dry and the beads will have to be re-trained to hold your desired RH.

In fact, what may have happened is too much water has been used for too long, and the beads have trained themselves to their maximum - which is about 70-75%.

Take some of your beads, throw them in a Tupperware with a hygrometer, and see what you get.

BTW, keep in mind that:
a) all the wood in your cigar boxes are holding moisture as well, and wood absorbs/releases moisture quite slowly.
b) we really want a cigar's weight to be about 11% to 13% water. RH is about the air around the cigars, not the cigars themselves. I can put cigars in a ziplock with some 65% beads and a hygrometer and put the ziplock in the freezer. The meter will stay at 65%...

Today's wild guess is the cooler isn't completely sealed and your active cooling unit is keeping the cooler at a lower temperature than ambient, with the result of constantly pulling in moisture from outside.

That is just a wild guess, though.