After re-connecting Stringify to my Honeywell account following this week's incident, it seems that Stringify is now able to send commands to the thermostat again.The problem is that it is not displaying correct information.
It shows the current temperature as -10 deg and the current setting as 0 deg (both incorrect, obviously). If I increment the temperature using the + button, it does nothing as it steps from 0 up to the actual current setting of the thermostat, then the thermostat reacts when I hit + once more to go above the current temp setting.
So apparently Stringify isn't actually sending anything to Honeywell until it reaches the actual temperature setting, because the thermostat would have reacted if it had received either a new absolute temp setting or an increment command.
That implies that Stringify actually knows the correct current temperature setting of the thermostat somewhere internally, but isn't displaying it correctly.
This is only happening since the incident on Sunday. Even at 8pm PDT Stringify was displaying the thermostat correctly (I know because I used it to increase the temp before heading home that night).