Ecobee 3 “Couldn't connect to Smartthings service. Try again later” (June 2019) (V3 app)

Trying to connect new Ecobee3 thermostat manually using v2 and new app. I select Ecobee and Thermostat but get a message saying “couldn’t connect to Smartthings service. Try again later”. Same the next day.
I can’t find any information about the message and whether it refers to the hub, the thermostat, the network, or something else. As a new user, I lack the knowledge and experience to interpret this and would welcome insights/advice!

I’ve been getting the same error for two days now. Were you able to solve this?

I don’t know much about the new app, but that’s an officially supported device. Have you tried calling support?