(-) inside of checkbox when bulk selecting songs to skip in shuffle mode. What does it mean?

[Bmorales4601]

So I was tired of getting christmas music mixed up with all my other music while in shuffle mode. I know I can make a playlist without them, but id rather not have to. Overtime I try to select all the songs and check the skip while in shuffle mode box, it has a minus sign looking thing all filled with blue. What does this mean? I also want to do the same for all my mashup albums as well, thanks everyone!

 

[Bigeric23]

That option is supposed to skip those songs when shuffling your playlist; however, I have read where several people are having issues with that setting.