I noticed many players with Rank 501 on galaxy location lists. Is that bug or it mean inactive player?

You were viewing the ranking during a reset. It should be fine now.

Not really. All players I scouted on are still same rank #501 for past 3 weeks. Not a single change.

This is really annoying.

Whenever I want to see someone's rank, every 10 minutes I have to manually go through the ranking lists to update the galaxy page so it doesn't say '501'. And since the rankings are now by every 30 players, it takes forever.