I've been kicked while shooting at opposition because the timer doesn't always reset.
Well... You do actually have to hit the things you're shooting at. ;)
Heyo!
It's because you didn't interact with the server properly.
Basic things you can do to keep "active in a district": simply shoot a car once, steal a car or kill a pedestrian.
These are simple things you can do, to avoid the inactivity kick.
Same goes for normal servers.