I am unable to invite friends on the topmost player slots, because the corresponding button is behind the surrounding frame’s background.
Workaround: Invite friends to a different slot, if enough are available
I would post a screenshot, but apparently this forum does not allow me to add screenshots to posts.
I would post a link to a screenshot, but apparently this forum does not allow me to add links to posts (“An error occurred: Sorry, you can’t include links in your posts.”).