I have 3 different probes in the same place to double check. I will check with a sponge later. All probes have more or less the same readings. I guess it is like you said - not enough loadDid you calibrate the dehumidifier, or double check it with another? Also if your in Ca with low humidity and a don’t have it loaded very full that might explain it, in which case just let it ride, 58% rh is ok and better than the outside humidity. You could put a damp sponge in to see if rh rises to check if your rh probe is working.
Thanks for your support!