Vote keys on Skyblock are glitched, and there's nothing the staff team can do about it. Trust me, if they could fix this, they would. The staff team doesn't like that it happens either. The only thing I can tell you is when you're using your vote keys, don't use them quickly. Wait like, 10 or 15 seconds between keys. Waiting 10 or 15 seconds doesn't stop the problem completely because they still sometimes disappear, but it really does help by reducing the number of keys that disappear.
Just an FYI, being nasty to people in chat won't help the fact that you lost a key.