It seems that your list view is corrupted and not showing the following groups when the first one is clicked on. How many records do you have in this list? Can you reproduce this issue on all the groups?
You can navigate back to the list and see if the list itself has the same issue. If yes, reconfigure the group by feature. If not, re-add this web part to your page.
Ps. I think I have temporarily reproduced this issue by switching the Toolbar Type via Edit Web Part > List Views, but it eventually went away. Try switching this option at your end and see if it fixes the issue.