Listen, I'm a simple man with simple desires, and those desires involve robbing the Saint Denis bank without everything going to shit. Issue is, the banks seem to have the power to remove people from existence, which I don't remember being a security feature in modern banks let alone banks in 1899.

This happens consistently, any bodyguard NPC that follows me into the bank gets deleted from existence. I created a whole posse to rob the San denis bank and everything only for them to get deleted from existence the second that step into the door. Is this some new bank security measure? Because last time I checked the Teller didn't collect all the Infinity stones

SInce you are a simple man I will give you a simple answer.

The mod is severely outdated and filled with unresolved bugs. You could know this if you did a tiny google search.

As with most modding issues people have, reading comments, checking the date of release, reading bug reports and googling the mods you wish to install is somehow a very hard thing to do.

So the simple answer to your simple question is;

Remove the mod and use a more recent mod like Banks of the West. Which also has issues but seems to work atleast 35% of the time.