bug about traffic block bug in simulation

[EcustBoy]

Hi~ I've meet such a bug: the traffic agents can be blocked by each other in some specific area, and the simulation is finally time out :-)

I use machine (with centos 7 OS and nvidia 3090 card), carla-0.9.12, python 3.7
I setup carla by pull carla-0.9.12 server in docker, and run client in my conda env.
I've choose scenario_runner package (corresponding to 0.9.12) and leaderboard package from official website.

I choose town 05 map for testing my model, and choose the official scenario file(i.e. https://github.com/carla-simulator/leaderboard/blob/master/data/all_towns_traffic_scenarios_public.json). But in some area the traffic flow can be blocked by each other like the following example (the green box car is ego car, it's global x-y coordinate is about (83, 6) under carla's global frame ):

So What could be the possible reason?
Will it have something to do with my carla version or leaderboard package version? Or with the hardware performance of my machine?