After finishing the first Elisabetha mission: Buyer's Market I received a call from Billy that I needed to go to Tom Stubbs. But when looking for his marker on the map I could not find him. I tried sleeping, doing a race, calling everybody including Stubbs to see if it would then appear or trigger something and still nothing. I almost gave up until I tried the following tip given by someone on a forum.
Call Jim and go play airhockey together.
In my case I still did not notice a change so I did another activity which was drinking (also with Jim). Then I checked my map and there was Stubbs.
But be aware that the marker is barely visible. Although you will be able to see his name in the legend. If his name is there then it's just a matter of zooming in closely on the map and you will find him.
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