Please zip it and send it to support@losant.com.
The system time changing is most likely the issue. The timer does use the system time to determine when to fire, even for simple intervals. When a timer fires, it calculates the next time it should fire based on the system’s time. When that time occurs, it fires again. This mechanism allows both the simple timer and the much more advanced “every day at 2pm” configurations to use the same underlying timer system.
If the date were reset back several hours, the timer system would still be waiting for the time it calculated the last time it ran.