There is an extremely simple solution for that, which can be solved with one of two solutions:
Hard Refresh your browser (delete cache memory)
Log out and Log in again
For Hard Refresh just press CTRL+SHIFT+R and check if it's ok.
To log out and log in:
For the web version, just click on the 'My Account' icon in the top right corner and then press Logout. Then simply log in again.
For the mobile app, go to the top right Menu > Settings > Logout and simply log back in.