Basically that. I went down the mine trying to do the 'The Final Descent' quest, but forgot taking the picaxe with him. When I remembered, I got back in a hurry but he wasn't there. The indicator was at his home and after waiting several hours, I lost patience and got in his house and no one was there as well. The indicator was pointing at nothing, just the "dining room" with nothing below. The last save point was quite a while ago, please, help me!

It's probably because when you get done with the mine quest, he's scheduled to be waiting at his house for you to talk to. My recommendation: Complete the mine quest, then do the pickaxe quest.

really, really thanks! i'll try doing that and answer asap for a possible solution to this bug