There is a strange column heading in the front end attendee list that seems to be throwing off the alignment of the listing. They are at the very right of the header column. I am attaching an image of the problem for you to see for yourself. Thanks.
First, make sure you have the latest build in place. If you have this issue still submit a ticket so we can see your exact setup and try to pinpoint why this is happening on your site. We can't replicate something like this on our sites.
I have had that since the beginning of 2.7 only when a group registration is expanded. When the group of attendees is closed (i.e. the + sign is showing) then I don't see that box. I have always been on the latest version.