So me and my brother and cousin play on MapleRoyals and we are whitelisted to vote every 24 hours, the issue is I voted at 12pm my time yesterday and today the website tells me to wait 190 minutes. In-game there is the message that tells me that I can vote now. I think this is related to the whitelist because I know yesterday my cousin forgot to vote and voted much later than I did..
Unless you have been sharing computers there wouldn't be any issues. The in game message is not always accurate.