Anybody got around being stuck at "Update Relationships" in a modded campaign?

[TBRSIM]

Thankfully, like in RTW, modding the campaign by going into the save file is quite easy. Money, income, shipyard, tech and campaign length (by editing respect of the losing AI and the VP) can be easily modded. This greatly enhances my enjoyment of the game, as it does for RTW. I would call this kind of access essential.

But when I want to play as e.g. USA vs. Britain (or Japan vs. USA) everything, including ship design, works until I go to the next turn after having built the initial fleet. Then the turn progress gets stuck at "Update Relationships". Going back to main menu unfreezes and Continue Campaign loads the next month, albeit without any battles. Only time this did not happen with modded nations was when I as the player had not built any ships and in turns where a blockade commenced. In the latter case I even had a campaign battlehip duel USN vs. RN...

I have searched the campaign save file and did not find any incongrous obvious errors (such as having missed modding the relationships section).  Anybody got an idea?