From the screenshot alone, we can't say why the issue is happening. It may be for many reasons:
* It may be that the data has not been bound
* It may be that here is an error on the page
* It may be that you have a template and the bootstrap styles on the page are causing that template to shift down beyond the viewport of the appointment.
To validate the last scenario, just put the same scheduler on a single empty page and test if the issue is happening again.
If it's not happening, then it's the bootstrap (or style related) issue. If it's happening, I can convert this forum thread to a support ticket so you can attach the page with the assets needed to run locally, or alternatively send us a live url for debugging.
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