I could be wrong, but I don't think cable is the issue if things work when even the long run is with the LEDs by themselves they work fine.
The run goes about 35 feet back into closet out of the wall into all three packs, back into the wall, 45 feet to the front of the room, in and out of the celieing, down the wall and back out to 4 fixtures on the ground. Total run, ~175 feet