Nav Mesh soesnt build after the game starts

Title says it all i have meshes that spawn after the game starts and navigation doesnt build during game play. i have “run time generation” set to dynamic and it still doesnt. Not only does it not do that but if i press play while its generating navigation it doesnt finish building. Im fairly sure that im doing something fundamentally wrong. Let me know what else i need to show you to help you make sense of this. Im sure this is something that can be done. im also concerned that this has to do with my computer being a mac and causing the program to act strangely.

The middle is obviously whats not building properly

Well I fixed it. Not a clue what the problem was just dragged out the BP in a new level and it works now so yeaaaaaaa…