I have some custom attributes, but it seems that they seem to multiply depending on how many classes a player has. When I set an attribute to '1' it will multiply that by how many classes the player currently has. This can be badly exploited, as attributes such as power or custom ones that add buffs or debuffs become wildly overpowered if the player has many classes.

In the image below, I have a base class already. setting my attribute to 1 makes it '2' and it adds 1 to the multiplication for every further class i have unlocked. for example if I set my attribute to '10' with 4 unlocked classes, it becomes '40'

Finally tracked down the cause of this. Having a base class with 'stack: true' causes any attributes to be multiplied by the amount of active classes you have. Unsure if this is a bug or intended, but that's what was causing it.