[GAMEPLAY] Items Randomly Getting Sold

After backing and closing the shop after buying items, my Chilling Smite w/ Warrior was sold automatically. Since it happened as I exited the store, I didn't even notice the boost in gold or the missing item until I backed again and bought more items.

The game was me as Kha'Zix with Dark Harvest, but it's also happened to me as Evelynn and Warwick before as well. I assumed I had just accidentally sold the smite item the first time, but this can't be normal.