Form in Foundation stopped working

After upgrading to RW 636, Foundation 1.5.5 and Stacks 3+, my form on my contact page stopped sending. After filling the form out correctly (no errors) and hitting Submit Button, I get an Opps error and the message is not sent.

I have tried an ending of .html and also .php and both cause the same error.

I also removed and replaced any legacy stacks with the latest in the library. Still will not send.

Does anyone have any ideas? Thank you

Have a link for us to test??