Embedded Registration Stopped Working

Site URL: https://wpcdinner.com/wwaregistration

Hey,

We have had some registration embeds up for months via the code block, and all of a sudden we're getting errors that looks like this:

 

We're sorry for the inconvenience

This form is currently unavailable, but you should be able to use it soon. Please contact the organization if you need immediate assistance.

The embeds work on non-squarespace sites, so it's not the code itself, so in the time being I've linked visitors to that second page, but does anyone know why this has stopped functioning? Anyway to fix? The code embed is from Blackbaud Online Express.

This is amazing, thank you for posting the solution! Been struggling with this ALL day with a website client.