MQTT Integration not loading

HI,
I noticed my MQTT switched were no longer working in HA. Upon investigation, I noticed the MQTT integration is not loading.
I have tried uninstalling and reinstalling but the integration wont load. It saves the configuration.
I can connect to my MQTT server without issues through another MQTT client and my devices respond to topics published. to that server via another client so it is definitely something amiss in HA.
I run HA in docker and the MQTT server is also a docker image but is located on a separate server from the HA docker. This has been working fine up to now
ANy help much appreciated