I just read the announcement about Rich text field formatting and immediately tried it in my app. Happy to see this new format is indeed available in the Actions. However, as soon as I change the field format to rich text, save and try it out in my preview interface, the input form closes immediately after I click Update Record button, and the whole block disappears from the page.
My corresponding field in Airtable is set to rich text format.
I had to revert back to Long text. Hopefully this bug will be fixed soon, I am really looking forward to being able to use rich text format!