See towards the bottom of one of your images where you have two "Component Devices" listed? These are also called "child devices" (more or less...), and you're looking at the "parent device." The two child devices created by the parent driver will give you a device for each of the two outlets that you can control individually like any device (and rename, use in apps, add to dashboards or voice assistants, etc. -- all separately from each other or the parent).
When you delete the switch and pair it again to your hub as a new device, is the Muxa's driver selected automatically during the pairing process? This is a must, otherwise, the effect will be as you describe it.
Check also which version of the driver you are using.
When you operate the two individual gangs from the physical switches, is the on/off state reflected correctly in the child devices?
@kkossev, once again, thank you for your help and support. I deleted and re-paired the device 5-6 times and eventually it just began to work. Very temperamental indeed👍