Hi Robert,
We are unfortunately unable to provide support through our Pre-Sales forum channel, but you can head over to The Events Calendar WordPress.org support forums for assistance and answers.
If you have a PRO license, you can log into your account and get assistance through the PRO forums. If you need to reset your password, you can do so here. This will send an email to the account used when you initially registered for the support forums.
To get you started, yes, it does look like a theme conflict. I would suggest to get in touch with the developers of the theme to help you out with this. There might be a piece of code in their theme that causes this error.
Thanks for understanding and good luck.
Cheers,
Andras