[Beta] Changes to custom HTML revert

[hugetim]

Alas, this appears to be a known issue:

[BETA] Problems with Custom HTML

Thanks for spotting this! It does look like there are issues with editing Custom HTML forms in the Beta Editor. We’ll add it to our list, and in the meantime you’ll need to use the Classic Editor for this.

For those using the Beta Editor, it might be a good idea to unmute (or otherwise monitor) the Bug Reports forum category.