Why won't windows 10 always allow voting on the lock-screen wallpaper?

I like some of the wallpapers, and was hoping that it will provide similar wallpapers when i vote that i like it.. However, sometimes it switches to an older wallpaper, and does not allow me to vote on it. It is also a wallpaper that it cycles to. Some of the wallpapers do not allow me to vote on them. Why is this? I usually hover in the upper-right hand corner of the screen, and can vote. But sometimes I cannot..... I don't like some of those wallpapers that it won't allow me to vote on.

regardless, i keep having this windows lock screen lately that is the same one that it switched to, and i cannot vote against it. The one when i rebooted the system was also one i couldn't vote against.

i found this: microsoft forum. it shows somebody with the same problem. one day in the upper right hand corner after showing an image, it asked if i like the image, I said i did.. it usually will say something like it will keep showing content like it.. however, it switched to one of the spotlight images that is at that link (the one with the plane wing). and it has been stuck on it ever since. i can not vote on it. i tried to turn off spotlight on lock screen. however, it switches to blue screen for lock screen, but still shows the image, and won't change it. i believe at startup, there are also alternating images, and normally it allows voting too, but it does not always allow voting anymore.