Is it normal for my unit to run continuously?

Usually no. If your dehumidifier is running constantly and the water container is not filling up at least once a day, there may be something wrong with the dehumidifier. But if the unit runs constantly and the water container has to be emptied daily, there's just a lot of humidity in the room and the dehumidifier is doing what it's supposed to do.

Maybe a suggestion as to why or fix the problem of the dehumidifier running constantly and not filling the reservoir.

The smaller the unit the more it will run if high humidity is present. Sometimes the unit cant play "catch up" to the moisture it is taking out of the air. A room that is 20' X 20' should have a 40 pint capacity. If the unit is in the basement and it's very damp the smaller unit will run forever and most likely freeze up. Like putting a small air conditioner in a large room,you overwork it and the unit will run all the time in most cases trying to cool down a room that the unit can't handle.