Rh will always swing as the compressor operates. The only thing that is important is the Rh of your cigars. Put one hygrometer in one of your boxes and after 24hours check the high and low. It should be in an acceptable range. Beads will not immediately absorb or release moisture, but over the long run they will regulate within a range that should be acceptable.
Dont worry so much about swings in Rh but more long term. Also, if your cigars are smoking fine there should be nothing to worry about.
