I had the same problem. The solution was the way-points as sometimes the character does not know how to reach the destination and it stops.
To fix it you need to do one of the following:
A- To reach destination C instead of going A--> C , do A--> B --> C . Breaking up half the way and making it easier for the character to follow the path fixed most of the issues
B- Create better waypoints. Are you using RIGHT Click to join the waypoints? This helps ALOT with them. Add a few more (preferebly clear your previous ones) and break most of the waypoints in half by adding more of them