If I remember correctly (now, seriously, how often has ~that~ happened lately...
) - but from memory (and correct me if I'm wrong please), there are equipment mis-matches between the turms and attached equipment (aka: "appurtenances"), such as radar masts and the like. The Pacific side had the same issue, but with OM, it is a herculean task to match everything. There are a LOT of turms and a LOT of appurtenances...
Wintergardens do not help, I'm sure... Don't forget that most of the subs in OM are all set to the same "UpgradeClass" setting in their upcge files, so you generally do not get submarine upgrades.
