Massive IP gain bug
I was in a premade group with 4 people and also had an IP boost. At the end of the game I saw that i gained 814 IP. My friends and I discussed this and we believe the IP boost got multiplied by 4 because of the way the party bonus interacts with the IP boost. (I got 436 from the ip boost alone, whereas my friends looking at their inactive boost only saw 108 listed)
Considering the number is different for anyone with an inactive boost, it looks safe to assume that the extra ip listed on mine is, in fact, a bug, and was not an intended multiplication. This resulted in my getting more than double their IP. (378 vs my 814)
It could also be that the interaction involves first win of the day somehow, but I might as well mention that it was my first win.