AWS Step Functions State Machine execution hangs out

One of our Step Functions state machine stopped working properly - it just hangs out on one of the step.

The state machine(A) executes two other state machines(B and C). When execution of B completes state machine continues its flow and executes C. Despite of the completion of C, state machine A does not continues its flow - it just freezes(it hanged out for a couple of days until we realized that something is wrong despite C completed after a few hours). I reviewed the configuration and IAM role policy but everything is done according to the documentation and we have not change anything in this process for some time. That just started happening around 20th October and before that it worked.

I believe that is some issue on AWS side and created a support ticket for that but from my experience I doubt that they will help as have only basic support plan. I'm considering recreating the state machine but first just wanted to ask, if there is anyone how faced with similar issue recently.