Given the fact that all you talk about in regards to GTA V is the police, not being able to shoot someone specific, mechanics, etc, makes me think that you had no time to care about the story, therefore you can't have a well formed opinion on something you barely paid attention to
That sounds like a problem with your .pmp file. I have encountered this, and it is caused by one of two things: #1: if you made the map using any mods, there is a chance that they might have terrains that are not in vanilla 0 A.D., which breaks the map, or, #2: your .pmp file is missing or named differently than your .xml file.