[Damo]

You will need to disable any camera mod you have installed and only use the stock freecam by using Shift-F2. The reason you get the out of sectors is because when the sub angle changes during diving or surfacing and you're at the extreme ends of the interior and the view is based on the Command room view where you are centralized, so the interior will move up and down without taking you with it. It's just that with the new compartments, the interior is just too long and there's a limit to how many interior viewpoints you can use (CR, Captains bunk, engine room, etc). There are many queries about this very thing in the FMInteriors thread, I suggest you read through it as it may clear up a few other issues you may or may not experience with the mod.

EDIT, I misunderstood, you are not getting any compartments at all right? Disable all mods that deal with cameras or views, and list your mod list after that (a screenie of your JSGME would be ideal), and be aware the interiors are only applicable to the type VII. I've left the above info in the post to make you aware of the issue in case you are tempted to re-enable your freecam after Interiors starts working.