Thanks for the message and sorry to hear that things aren’t working as expected. Are you using the official Hubitat Ecobee integration or one of the community integrations?
My suspicion is that a device synchronization process was kicked off for some reason and the Ecobee devices couldn’t finish syncing so they got skipped.
Several of the community integrations report such a large number of attributes that it can cause the Hubitat Cloud Relay to timeout during device synchronization. SharpTools will automatically retry the sync multiple times and will skip syncing a device if it can’t be read multiple times in a row.
Usually reauthorizing your devices will fix things, but if the device times out while synchronizing, then it could get skipped.