Wallpaper Shuffle Issue

I have a collection of 48 photos that I want my phone to shuffle through as my Lock Screen. The issue I’m having is it’s only showing the same ~15 photos. Every time I “reset” the Lock Screen by just changing the photo album back to what I want, it shows some of the other photos, but still out about 15. From my understanding, you can have up to 50 photos shuffle. Any advice? Thank you for the help