That is exactly the tutorial i followed at first. Now i implemented the solution based on PubSubClient. For this i used this as a base: ESP-MQTT-AWS-IoT-Core/PubSubClient.ino at master · debsahu/ESP-MQTT-AWS-IoT-Core · GitHub
If I subscribe to /# I still get only the messages I publish in the loop (via sendData()). Eventhough on AWS I see everything else.
I also tested with MQTT Explorer using the same credentials I use on the ESP32 (cert and key). Everything works as expected there. Therefor I would think the issue has to be in the implementation on the ESP32...
Any ideas?