Hi @hma13,
Events Calendar 5.0+ have came with a lot of new features and a brand new design.
This option of The events calendar plugin is very new and is not compatible at all with our themes (yet).
They have done a huge redesign of all their code and it will certainly take us a long time to integrate it into our products.
In the meantime, we simply advise you not to activate this option by unchecking the “Use updated calendar designs” box in the plugin parameters (Events Settings > display tabs).
Best regards,