Multilanguage form does not work

Hi, my form (using captcha v3, language.yaml, message,...) is working fine as long as I use one language (default EN), the path to the form is "www.sitename.com/form"
If the site support more languages (added french and dutch), the form does not process. The form is located at "www.sitename.com/en/form".

Strange thing is I do not get an error. When submitting the form it doesnt do a validate, just clear all fields (reset).
It must be something I am missing... do I have to set an "action:" for multilanguage forms?
Thank you !

Hmmm... I just set up a new empty site with default theme Quark and the form is working with multilanguage support.

So it must be something with my own theme templates, damn... my own fault :-)

Sorry for bothering... 😄

I have the same issue and it occurrence randomly on the Rockettheme.
Perhaps this happens under the cookie influence?