translations not found

Hi Maxime,

I have the following issue:
existing translations do not show – I get a 404 page instead.
I created the Hungarian translation for my page about classes; the original url would be eszter-maura.tk/lessons, and the translated page showed the url eszter-maura.tk/hu/oktatas (with the translated title), however, the page redirects to 404. I tried with eszter-maura.tk/hu/lessons (taking the original EN slug), but it did not work, either.
Content that does not have translations seem to inherit the EN well, though if I change the language at a page/post other than the homepage, it first takes me back to the homepage (with the lang code in the url, so that should be ok — home page doesn’t yet have translations)

I am using SiteOrigin builder / vantage theme, though I did find the same issue when I tried it with twenty seventeen (to rule out incompatibility).

I had to deactivate the plugin for the moment, as I’m promoting a course and I do not want to confuse visitors with languages that are not found, but if you are willing to have a look, I’ll reactivate it immediately.

I’d be very grateful for some help.
Eszter

The page I need help with: [log in to see the link]