macAilpin: Angry Gods?
Where did you build your dock(s)? (What side of the water? Maybe a ferry problem?
I can't remember but did City Gates stop traffic in Zeus?
Some possibilities.
It's not the docks, but in the regular land trading posts, I've got no walls or other obstacles which would not let the caravan to pass. And there were no gods attacks so far...
muttly13: Do you know the name of the specific scenario? There are several were this type of thing happens. You mention Fleece and Oil specifically, these are often used to limit your housing growth in a scenario where it would be to easy to complete if you had immediate access to a large population. My guess is this is scripted behavior and it simply wants to keep you at lower housing levels.
As an example, in the first one "Unlikely Beginnings" you wont get fleece until Thermopylai becomes a vassal and offers it in tribute.
It's in the "Revolt in Ionia". I mention these ressources because these ones I need, however it applies to every ressource from Corinth and Olympia (both vassals with "loyal" appreciation). In fact, I've got trading posts from different cities, but I don't get any caravans from these ones only, even if they should be trading.