Devices known to SmartThings that worked OK with Roomie yesterday now report either 'Device didn’t respond" or ‘That device doesn’t accept that command’. Similar problems with Roomie devices.
Should double check that the the Echo has access to the devices.
Had weird problems with mine that started about the same time.
My Asleep/Awake modes use the Echo through the ST integration app, Alexa Helper, Rule Machine, and Send events to Eventghost. When I told Alexa to “Turn on ___ Mode” it would say “I don’t understand” or “I can’t find the answer to your question”. If I just said turn on mode, it would then say “I found several devices…” and would work properly once I re-stated the correct mode. Modes worked fine via SmartTiles.
Finally got it fixed today by updating all of the associated smartapps, republishing them, and re-scanning for devices on the Echo (not sure which step actually fixed it).
Not sure if that helps…