Good evening Stefan and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
We are sorry to hear about the price disappearing on you.
I would love to help you with this topic.
As a first troubleshooting step, could you please provide us with your complete system information in a private reply using the instructions found in the following link?
https://theeventscalendar.com/knowledgebase/sharing-sys-info/
In the meantime, you could apply the following snippet in the functions.php file of your theme (without the PHP tag at the top): https://gist.github.com/GeoffEW/69f8a033fb614c78b3de45a197431135
Best regards,
Geoff B.