Bruce states Boolean is not a supported type for an attribute in a driver. The suggestion in that thread (and in Rule Machine - Boolean Condition Custom Attribute) is to change the attribute from bool to an enum like this, which allows Rule Machine to act upon it as a custom attribute.
This change is in line 88 of the WyzeHub Camera driver:
(I created a pull request with it)
From:
attribute "floodlight_powerstate", "bool"
To:
attribute "floodlight_powerstate", "enum", ["true","false"]
With that change, I can finish adding the rule to make a virtual switch mirror the state of the floodlight:
