@isalan: I've had a look into this and the SmartThings community have confirmed that the app and Yeelight are in deed compatible under specific conditions. I recommend checking out the following post, which provides a breakdown on the necessary steps.
https://community.smartthings.com/t/mi-connector-xiaomi-and-yeelight/122305
https://community.smartthings.com/t/mi-connector-xiaomi-and-yeelight/122305
