When I place a bounty, I do not get an event log for this.  To reproduce, try to place a bounty on anyone and then go to log.  Either with all or just the Bounty category and nothing shows.

It does still show if someone puts a bounty on you, and if that bounty is claimed though, just doesn't show that you put a bounty on someone

Will take a look at this one when I get some time.