From: The Land of Yore
Can’t say what your problem is, however, I have played the game since release and have had a learning curve about sub ops; you may want to try some of these solutions:
1. Make sure on the game setup page that you have auto sub ops turned OFF.
2. I’d suggest leaving it as a supply sub TF until you get the supply off it.
3. Make sure you have the TF selected to unload supplies.
4. Make sure it’s not in a patrol mode with way points set; if that is the case it will move from way point to way point until fuel is low.
5. Assuming the sub is in a patrol mode, use the same way point screen to eliminate all way points, it should then return to home port.
6. If that didn’t work or isn’t the problem, can you set a new home port? If so, set a new home port and return it.
7. If you can get the sub to a friendly port, unload the supplies there (may have to click the unload button).
8. If you can get it to a friendly port but it doesn’t unload, try disbanding the sub group, and then reform it. Once reformed off load the supplies at that port (click the unload button). Once unloaded, disband and then form again as a new sub group and assign any home port you want.
If the above doesn’t work, I suspect some kind of bug and recommend you post a save game file for possible review.
Why am I sharing my opinion? Because I am such a special snowflake that others need my knowledge. What…there are like a billion snowflakes? Oh, well isn't that special.