Login Issue

Hello.

I have this strange problem and I cannot identify what’s wrong.
When one of my website users is trying to login, she types everything correctly and she logs in. The problem is that only on the homepage, she still appears to be “not logged in”, while on all other pages of the website she is normally logged in and she can see her avatar, buttons on header etc.

The website url is https://gordian-knot.eu and the username is Narweena

Thank you for your help in advance.
Athlios