Receiver end stops receiving

I have a minimal example code in this gist https://gist.github.com/JoseKilo/319493e6ef3f17d86a76ad7c7b20055e

It's a modified version of the stream-dealer-router example https://github.com/aio-libs/aiozmq/blob/master/examples/stream_dealer_router.py

The differences are:
- Instead of running everything from the same process, I use two processes: sender and receiver.
- Instead of running for a finite number of iterations, they run infinite loops.
- I have removed (commented out) the reply message.

When both are launched, they start working as expected, but after some time, the sender keeps iterating and the receiver stops receiving.

When the reply message is enabled, the problem disappears, but the communication is also slower.

Depending on which process is started first, the problem appears sooner or later.