In the reminder email, the appointment start time is one hour after respect to what I've set in the task.
E.g. (italian hour format):
- task start time set at 14:30 (email reminder 5h ahead)
- received reminder at 9:30 (4h ahead) with start time at 15:30

I guess there's some trouble with timezones and/or daylight saving time.

Cheers.