I wanted to create a meeting, so I filled all the fields, set time to 18:00 - 21:00 and hit Save. I received an error about Location format, so I fixed it and hit Save. And my meeting was created at 08:00 - 09:00 time slot, which are the default time fields values. Most probably the form refresh caused a reset of my configured time.

If there's an error in the event form, please don't reset the time field values.