Good evening Jorma and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the empty time slot being created on your calendar.
I would love to help you with this topic.
I believe the issue stems from a customization of the day view in your WordPress theme.
The reason I am bringing this up is because your screenshot is very different than the way the day view looks by default: http://wpshindig.com/events/2017-10-10/
Could you please send me a copy of the latest version of your WordPress theme / child theme via a link to a .zip file link (stored Dropbox or Google Drive) so that I can run some tests on my end ? I recommend a private reply for that purpose.
Please ensure you are using the latest files as found on your actual website.
This way I will get access to any updates or customizations you might have made.
Hang in there!
Geoff B.