Ok, thanks for letting us know. This is therefore linked to the known issue with new emoncms inputs not being created via mqtt.
Basically by renaming the “t1” input to “temperature”, you effectively removed the “t1” input so when the input was next updated via MQTT what should have happened was phpmqtt_input.php should have created a new input “t1” since there was no existing input with that name.
Had that happened, you would have seen the new “t1” input pop-up immediately when the older/renamed “temperature” input stop updating and all would (hopefully) have made sense.
An alternative to a Redis flush would probably have been to restart the mqtt_input service as that is the current fix for “new mqtt inputs not appearing in emoncms” issues.