I was hoping to use Configurable Ping to monitor several of my devices in my network. I use Aedes MQTT Broker quite a lot, and the minute I add the Ping node, the MQTT data stops working in my project. It's arriving still, as I have confirmed using MQTT Explorer.
The minute I remove the Ping node, the MQTT data resumes being displayed.
Try using the official ping node node-red-node-ping instead.
Alternatively, use a proper broker (like mosquitto or emqx)
As for "what is going on". If you are stressing Node-RED (or rather if this configurable ping is being hammered or is just a 'heavy' node) then due to the single threaded nature of NODEJS, the event loop will be starved and the MQTT connection will be unreliable due to you also running AEDES on the same NODEJS thread.
Displayed where? Is it an MQTT In node or an MQTT Out node that is not working?
If it is an In node, have you confirmed, by using a debug node, whether anything is being received?
However, I second the suggestion not to use Aedes. Others have had problems with it, and really there is very little benefit to using it instead of, for example, Mosquitto. Mosquitto has much better performance, more features, is solid as a rock, and not difficult to install.