Yeah, the Nav Mesh is why they weren't following you. And it would've been an easy fix which, for some reason, I never thought of doing. I don't have any plan yet to continue with this game, however I will definitely do something similar in the future. I'm actually currently in the process of learning Unreal Engine, and this game was just about everything I had learnt to do so far, but right now I'm currently trying out some new things before I go back to an FPS.
It's great to hear that there is someone who is interested in this game, and I'll definitely take into account what you liked about it in any future games, and I'll consider perhaps making another game like this one. Once again, thanks a lot. This was extremely helpful.