Validation error doesn’t show for the second language

On my multilingual website (using Polylang) I created the login, registration, lost password, etc. pages for the second language. The content of all pages is the following shortcode [theme-my-login default_action=”<action>” show_title=””] where <action> is the proper action name login, register, lostpassword, etc. regarding the current page.

Basically, the second language pages are working, but when I e.g. try to submit the registration form with empty fields, the validation error box doesn’t show. I don’t understand it, because it shows up on the first language pages.

I made some research and I found, that the tml instance is not active in case of the second language pages, so the error message box doesn’t show, however the error messages are there.

Do you have any idea what do I wrong?