[Plugin: Contact Form 7] "You do not have sufficient permissions to access this page."

Try deactivating all other plugins and switching to the default theme.

I managed to insert a redirect to the thank you page, but redirect doesn’t work.
I used this code:
on_sent_ok: “location.replace(‘https://www.maximdesign.it/grazie/’);”
which works properly on other sites.

feorm redirect doesn’t work. Any idea?