Me and a lot of the other players in my town have seen that when we have a lot of a single item, we seem to get more of it. I’ve seen this when I had no ultra balls left and I spun 200 pokestops in one day, and got none. One of my friends had the same experience, but with 80 pokestops.
My items right now look like this![Screenshot_20180529-080947|468x500](upload://u9wDIspY5LhpzNywxzJifX70t46.jpg
And it seems that I may even be getting more ultra balls than pokeballs. I also have no potions at all (I’ve done a lot of raids recently) and on my friends’ phones they seem to be getting 12 super potions or thereabouts per raid, whilst I am getting golden razz berries mainly, which I am nearing 200 of.