ECS deployment stuck without pending tasks and ECS events (possible bug)

Sometimes after I trigger a deployment of ECS service the new task set is stuck with 1 desired task and 0 pending. There are no new ECS events (the last one is "service xxx has reached a steady state.") Creating new deployments does not help. It just replaces the primary task set which is also getting stuck at 1 desired and 0 pending)

The service is using EC2 capacity providers and ECS deployment controller. My settings are min 100% healthy max 200%. There is 1 task running prior to deployment. There are multiple container instances available and agent logs on the instance do not show anything unusual. The cloud trail does not show any failed calls for ECS service.

Changing the desired count from 1 to 2 immediately creates 2 pending tasks.

Is there any extra information I can find? Is it possible that this is caused by a bug since there is no trace in ECS service events?