I think your humidity is too low. This is the most common reason for soaking. There are so few whom understand relative humidity that it is no wonder why so many have issues with it.

Relative Humidity is relative to temperature. It is expressed as a percentage of the saturation point of the air that changes as the temperature changes. (saturation vapour density) As the temperature changes the SVD changes and the %RH changes too. If you have 50% of 10 (5) is very different from 50% of 10000 (5000) yet all anyone speaks of is 50% I have 50% of the money I won. It is meaningless.

RH% with out temp is also meaningless.

You have said you have a cool side temp of 75-78 constant from that I would infer that the ambients are also in the 70s. This means that if you have an average of 60%RH @ 76ºF you have about 13gm/m3 Absolute Humidity. You need to have 15.5 AH It is too low.

If your ambient air temp is 76ºF you should be holding just short of 70%RH to get 15.5gm/m3 AH. Increase the humidity and the issue will resolve itself. (if you increase the air temp some it becomes easier to hold the humidity. My ambient air temp sits in the 83ºF area and I can very easily hold in an open tank 15.5 AH (54% RH) Ambient air temp is the key to most husbandry issues.