This does happen from time to time, and sometimes the cause is never found. It’s mostly related to issues in the SmartThings cloud.
As you may know, on Friday and Saturday this week there were a number of partial outages. Sometimes what happens is that a command that is not sent during the outage (sent from the cloud, not from the hub) then gets sent from the cloud to the hub hours later. Very annoying, very difficult to diagnose.
You can contact support and ask them to look into it, but it can be very hard to diagnose.
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