Long story short: if you k-scan a ship to reveal bounties, and then k-scan again but don't complete it (by mistake, like just tapping the scan button without noticing), you lose the bounty:
https://forums.frontier.co.uk/showthread.php?t=76615&page=103&p=1630414&viewfull=1#post1630414
So the solution for now is to be careful not to push the scan button again after having completed a scan.
https://forums.frontier.co.uk/showthread.php?t=76615&page=103&p=1630414&viewfull=1#post1630414
So the solution for now is to be careful not to push the scan button again after having completed a scan.