Toy Missing from Collection

1. Ensure that the your filters are appropriately checked
   1. Open the Collections Menu (Shift-P)
   2. Click the Toy Box tab
   3. Click the Filter button (top right)
   4. Ensure that Collected is checked 
      1. Under Sources, select "Uncheck All" 
      2. Under Sources, select "Check All" 
2. Perform a user interface reset

Note: Mounts, pets, heirlooms, and toys in the Collections tab are account-bound, and do not generally transfer when characters move to a different Blizzard account. The only exception is any pet or mount associated with a character-specific achievement, which will only appear for that character on the new account.