Ok, so I find a sage in a region, and get him to improve one item, then he goes to another region. After about a day, during which I was investigating, I find out where he has gone and travel there.
I arrive, but have too much fatigue to do anything. So, half a day after he arrives, he leaves, before I can even do anything. Now I have to wait approx another day until he arrives somewhere else. And this is not the first time that It had happened.
Very much hide and seek. Do sages routinely run around so much? I'm guessing there might have been an adventurer who forced him to run away, although they aren't in the region right now...
It's pretty routine. It used to be easier to find a sage, but nowadays it's practically impossible - or, at least, not very worthwhile.
You simply have to be smart on how you use your hours. I have followed sages and wizards for several months and never lost them. That helped me create 6 scrolls. They may pack up after you use them but they will still be in the area and you will have to wait to be able to listen to rumors. And they only move on turn change so if you are getting close and your hours are low dont waste them hunting or gathering as you might need them for travel.
Also, try to make contact with other adventurers so they can tell about the sages they meet.
At Corsanctum/Morek, we have a guild.