That is what I would have thought as well.
I don't think it's working as designed unfortunately either. If you start at your first owned title and click Next Title it toggles through your owned titles. After your last owned title it jumps to some random non-owned title. When clicking Next Title again. it does not jump to my first title at all, instead it picks another owned title, sometimes the 2nd or 3rd alphabetically.
I have 4 titles entered, If I use Next Title arrow I get:
Amazing Spiderman (1st owned)
Incredible Hulk (2nd owned)
Spiderman (3rd owned)
Uncanny X-men (4th owned)
Random non-owned title (sometimes 2 non-owned titles come up)
Randomly the 2nd or 3rd owned title comes up (it will progress through to my 4th title after hitting Next Title, but it never goes back to the 1st in my collection, ASM)
Random non-owned title
and repeat...
Devs if you want to recreate this, just start with a fresh database, add 4 or 5 comic titles, change items to show to Owned items, then toggle through using the Next Title arrow a bunch of times. You'll toggle through your collection to the end the first time then it jumps to random issues and then it does not go back to the first issue in your collection.