How do you sort reference prices?

I am a casual seller on amazon, I don't do too much of it, but we sell a little bit as such I am not versed in uploading spreadsheets to update products we don't have a huge catalogue so I haven't learned how to do it, as doing each item manually is OK for me. I always have these issues with Prime discounts, loads come up saying no reference price and when I check, either the parent listing or the variations they all have a list price/reference price on them. I delete it, save, come back in a day or two, add it again, wait a day or two and try the discount again but nope, no reference price. Why does this keep happening?