Hi thoso,
we had this bug twice before and always the users settings were wrong (it was displayed correctly but in the database entry it was wrong).
Did you try creating a new user for testing?
The event times are, as Sebastiaan stated, saved in utc time (or what Joomla / PHP thinks is utc time) and then calculated for the active user or if he has set no timezone, then on the Joomla setting (Global configuration -> Server).
If you create a new article is the time there correct?
Best regards,
Yves