I'm trying to use this code on my site for the same issue (not eventbrite) and although I added the button ID, it still isn't dropping the shadows or borders. any ideas?
my code:
<a href="https://compelcommunitychurch.churchcenter.com/people/forms/391625" data-open-in-church-center-modal="true">
<button class="sqs-block-button-element--medium sqs-button-element--primary sqs-block-button-element"
type="button">
SIGN UP HERE
</button>
</a>