The issue with dehumidifiers is they are basically air conditioning units that once they cool the air by passing it over the evaporator coil to collect the moisture they reheat it by passing the air over the condenser coil, the energy consumed slightly warms the area.
The problem is the evaporator (the part cooling) will not be as effective because of the cool ambient temperature and may ice up.
It sounds like your system is working ok but would be more effective/efficient at a warmer temp.
If you’ll notice many home ac units don’t have set points below 62 similar reason because the evaporator is so cold it ices up and doesn't cool as well. So although you are at that threshold it sounds like your system is working, but it may not be at peak efficiency because it is at the lower limit.
If this explanation doesn’t make sense take a glass of ice water put it on a table and time how long before it starts sweating. Wipe the glass dry and put it in the refrigerator and wait the same amount of time and check the glass, less condensation because of the limited temp differential (well the air in the fridge is dryer) but trying this experiment upstairs in a warm room and then in the basement will show the cooler room condenses less moisture even though it may be more humidity (again there are factors that affect this but it may help to visualize).