These "bugged" assignments can also happen if you changed the games configuration, such as you had a fully stock game, and applied a mod, but didn't delete the Save folder, you would probably run the risk of troubles with the game running correctly. Likewise if you remove a mod, and then try to use the Save from the modded game. The game runs of off the Save folder, and if it can't find the appropriate info, it will do strange things. It can get very frustrating, especially if you haven't played the game in a while, where there is an old Save folder from years back. Lord knows what's to be found in the dregs there... If you don't have much of a career going yet, you might be best off to delete the Save folder, and try again. It is generally "C:\Users \UserName \Documents \SH4" and all of the folders and file below that. You do lose all progress made thus far, as well as re-setting the display and other options in the game, but sometimes you do what you gotta do...
All that said, besides the modders making mistakes (who? me?...
), the devs also made mistakes in the game. There is one ship with no sonar indication, some will not allow a player to track them, though the sonarman can follow them. There are also some bad spawns that can happen in the stock game. It is by no means "perfect", but I wouldn't expect it to be. It actually does rather well for its age...
