It isn't to do with one's IP it is only specific IPs that give the problem. When one publishes "58.169.129.172" to a topic (any topic) mqttexplorer shows {}. I think a clue is that if you click on the value and look in the right hand side it says Decoded SparkplugB
It is fixed in the edge version which you can get by running
sudo snap refresh --edge mqtt-explorer
