Just a reminder for those that also have devices that can connect independently to echo, most commonly the Phillips hue bridge, that you will want each device to only connect once to echo. If you have it connected both through the Phillips hue bridge and through the SmartThings official integration, results will be unpredictable.
The most effective way to do this is to simply not authorize the Phillips hue bridge and its bulbs in the SmartThings/Echo integration, but leave it connected independently. Everything will still work just fine: you will be able to control the hue bulbs by voice with echo, and you will still be able to use all your other SmartThings rules with them.
If you do have a device connected twice to echo, delete The ones associated with smartthings from the alexa app , then open the echo smartapp inside the SmartThings Mobile app and remove the duplicated devices from the authorization list.
Then have echo discover new devices again and everything should be fine.
More information in the community FAQ.