Screenshot: http://steamcommunity.com/sharedfiles/filedetails/?id=1153269602
At over 270 days in and I have no less than 15 caravans stuck in an endless loop en route to Pyke. They take the Hags Mire ferry over to the island with the Ten Towers castle, get halfway to their destination and return. Adding more ferries between the Iron Islands might fix it, like a new ferry between the islands with Pyke and the Ten Towers castle.
This has been posted 3-4 times already. Has Pyke been captured and/or recaptured in your save?