That’s the place to post it:
https://wordpress.org/support/topic/forms-fail-after-42-update?replies=1
But, BTW, did you try deactivating other plugins, clearing any caching on your site and testing with a default theme?
I did more than that. I tested it offline against WP 3.8 and 4.1.1, which both worked fine. WP 4.2 breaks FP. My test site has very few plugins, a simple theme an no caching.
I’ve reported it here as a heads up that there are issues with this. FP support has replied on their forum.
This problem appears to be related to the use of custom CSS to restyle the form. Reverting to the standard Formidable CSS makes it work. The question remains, what would a Wp update break that. I’ll let you know when I find the answer.