It's only a visual bug. When you rank up, it tells you the proper rank (and you don't get access to ships you previously couldn't). The biggest downside is you don't know when you're ready for a rank up mission.
For me, it looks like maybe it glitched and "added" your rank twice to the display. Pre-patch, I was Imperial rank 4. When I logged in, it showed rank 8 (still only rank 4 privileges). I've been ranking up for the Cutter and been getting the rank up missions (with proper promotion levels listed in the reward mails). I'm Marquis now, but my displayed rank went blank after getting promoted when it displayed King.