I have 3 devices, each with its own dashboard, and each has buttons that activate things on the devices. I am using MQTT. Today NONE of them will work. The devices (Arduino NANO 33 IOT) never receive a callback. They do get callbacks when they reconnect for each of the buttons. The Dashboard DOES get updated when the devices request it, so the interface is working in that direction.
If I click on a button in the dashboard and then reload the web page, it sometimes sends the callback, but not very often.