Redemption Codes "null" or "already used"
So I am trying to equip 30 supervised school iPads with an app we purchased using the VPP called Sparkvue. We purchased 30 licenses, I downloaded and imported the spreadsheet, I hit prepare and 18/30 went through...the rest "finished with error," which I drilled down to discover were unable to authorize the redemption code. When I look at the redemption codes list in configurator, several of the codes are greyed out with "((null))" written after them, and several others say "(this code has already been redeemed.)". I've tried re-downloading the codes, but it doesn't seem to have an effect...any ideas?