Orchestration is not resuming after external Event

**Setup**
In our setup we are haveing buildin a retry mechanism using the DTF's SubOrchestration and ExternalEvent handling features. When an activity on DTF unable to complete its work even after the automatic retries we start a new SubOrchestration in waiting for external event state.
When an external event is fired SubOrchestration marked completed and main orchestration resume its work and this work fine normally.
**Problem**
But in some scenarios where SubOrchestration is running and waiting for signal from couple of days, like more then 3 days or we send new release of our code without any change in DTF versions or Orchestration context, this retry mechanism doesn't triggered.
**Observations**
While analyzing the problem we found that, retry Event is being published on ServiceBus and its also read by DTF code but while processing DTF unable to resume the main Orchestration though it marks SubOrchestration as completed.