At what point does it change the time – when you’re trying to enter the time, or when the event is saved?
It changes when I click the update button on the right side of the screen in the panel where you can edit the time change.
It seems like it’s always a 5 hour difference so I suspect it is something to do with regional time zone settings. So when I enter a 9:00 am start time the system changes it to 4:00 am. It does the same thing on the time for when I want to close down event sign ups.
It does sound like it’s related to the timezone. That said, it shouldn’t happen at all.
It might be a conflict with your theme or another plugin. To check if that’s the case, can you test with all other plugins deactivated and while using the default WordPress theme?