So far, you've completed all the right tings, that I would have suggested. Now, take a look at the humidity setting on the dehumidifier. If it's set high (above 65%) there's not much chance that the unit will collect any humidity. It simply is just maintaining what it's set on. Lowering the setting to 35% will have a much better affect in removing the humidity/moisture.
There is an in home test you can do, to make sure the unit is working properly. Place the dehumidifier in the center of a bathroom and turn the shower ON hot enough to generate steam. Turn the humidifier ON and Set the level at 35%. Do Not turn the bathroom's exhaust fan ON or leave a window open in the bathroom. As you exit the bathroom, close the door and wait 15 to 20 minutes before returning. After entering the bathroom, turn the shower OFF and allow the unit to run for 5 more minutes. Then check the bucket for signs of water. If you find any, the unit is working as it should. Also. the dehumidifier, when in operation should have a minimum of 2 feet of clear air space around it. The fans on many units run almost constantly, to recirculate the air and if any increase in humidity is sensed, the compressor will turn ON. This is particularly true, if you operate it in continuous mode, rather than a timed mode. Also, be sure that all exterior doors and windows are closed when the unit is in operation.
If after doing the in home test, the bucket did not show any signs of water, either the humidity sensor has failed and needs to be replaced or the compressor needs to be recharged with refrigerant. If you don't feel comfortable trying to repair the unit yourself, the following is a link that will help you locate an authorized LG Repair Center in your area.
Find out what the cost to repair the unit will be, before committing to it. As your model has been discontinued and it may be less expensive to but a new unit. Hope this helped you. Please let me know.