I have 10+ golems on more servers. I think this is happening online as well, as was said before - sometimes the golems stop and freeze and do nothing, even though they have free spots in their inventory and resources to harvest.
Stone harvesting golems also may appear to be just walking around the area and doing nothing, but the sad truth is that they also harvest by picking up single rocks from the ground (insanly slowly), instead of aiming on bigger nodes. 
So far the only solution for unfreezing inactive golems was to give them “follow” order and leave them in “scouting” mode right away. They usually restart and get back to their job.