Hello,
Your groups are there, you just don't see them. The group-list is actually scrollable, but you can also:
1) increase Group list height to 50 in Options page / Groups tab, to see two rows of groups (you can also decrease font size or reduce spacing)
2) use group-dials instead to navigate between groups, you can see that in the introduction video with the group-dial "Work" (https://www.youtube.com/watch?v=wvT4w-R8hJU)
3) rename groups with long names :)

But as a user with 3 big monitors I can also recommend you to buy a bigger screen, like 27" with QHD resolution (2560x1440) - it's a great way to increase productivity and you can fit a lot of groups there.

I hope this helps.

Have a nice day :)