Okay, here’s what’s happening.
I created a new event for today, with times 20:00 – 22:00.
If I use any city as timezone, it always comes back with these times, 20:00 – 22:00.
It makes no difference if I use Madrid, London or Tokyo, the date and times do not change.
If I use UTC, the time stays 20:00 – 22:00, which should be 22:00 – 00:00, since I am in a timezone UTC+2.
If I use UTC+2 as timezone, the times change to 18:00 – 20:00.
So at least when using UTC timezones, something changes, but not correctly.
If you choose a city nothing changes.
Hope this clarifies some of the issues, if you need more info please let me know.
FIY, my system timezone is set to Madrid and in the Events Manager settings I have enabled timezone support, with Madrid as default timezone.
With Madrid as timezone for the event this is in the database:
event_start_date 2020-07-09
event_end_date 2020-07-09
event_start_time 20:00:00
event_end_time 22:00:00
event_start 2020-07-09 18:00:00
event_end 2020-07-09 20:00:00
event_timezone Europe/Madrid
Changing the timezone for this event to New York gives
event_start_date 2020-07-09
event_end_date 2020-07-09
event_start_time 20:00:00
event_end_time 22:00:00
event_start 2020-07-10 00:00:00
event_end 2020-07-10 02:00:00
event_timezone America/New_York
The frontend still show 09/07/2020 20:00 – 22:00.
If I change the event_start_time manually to 19:00, nothing changes both frontend or backend. When updating the event using Events Manager, it resets the event_start_time to 20:00.
I think there is some confusion about which fields the system should use, I think you either need the first 4 fields, or the last three, not a combination of both.