Mastery page selection bug in new champion select [CLIENT]

When picking runes and masteries in the new select, I noticed I had a page (Page 9) that was outdated. I deleted it and then went to select my masteries for the game (The now new page 9, previously page 10). I tabbed out and then later tabbed back in and saw that I was using "AP Support" (Which should be my 10th page) for Corki as ADC. Not wanting this, I switched my mastery back to page 9. It would keep on selecting AP Support, the page BELOW my ADC page. I ended up selecting the mastery page ABOVE the one I wanted. This gave me my desired result of my correct mastery page. It was fixed in the next queue.

Steps to reproduce.

1. Enter new champion select (I was enrolled as Bot, but it may affect other roles).
2. Declare Champion (I was declared as Corki, but it may affect other champions).
3. Pick champion and lock in.
4. Have three mastery pages, 1, 2, 3.
5. Delete mastery page 1.
6. Try and select the now Page 1 labeled as Page 2.
7. Watch as it selects page 3.

I tried again to replicate this bug, and was unable to.