Group page says "Group 2" instead of the group's name

What I did

Opened the app, clicked Open on Surf Trip Ericeira.

What I expected

A big heading saying "Surf Trip Ericeira", like on the home screen.

What actually happened

The heading says "Group 2". Same for the flat: it says "Group 1". Which one is which? I kept going back to the list to check I had clicked the right one. Everything else on the page looks fine, it's just the title.