If a light is activated and then deactivated, and during the off event countdown the time period changes, the off command gets cancelled and the light stays on until the next activation/deactivation event. Not sure if this happens with modes, but I'm seeing it with Time Periods.
Here's a copy of the log, its also the same bug that was previously fixed in this thread here:
Upon further examination, if you have Adjust on Time Period Change set as an Activation Option, the logs would be as shown. That is a bug, and I'll get it fixed. See logs after fix below: