FS#21951 - Bounty: Dragon bugged in some cases
During the quest Bounty: Dragon (BQ04), it appears that the dragon will not be correctly spawn (respawn?) at Mount Anthor. There are a few reports of this on UESP's page.
It’s possible that this is not unique to Mount Anthor, but just having killed the target dragon previously. I believe I did that, but I’m not 100% sure. The other reports on the page don’t mention it either way.
Also, at least for Mount Anthor, it seems that it wants to path you through some bizarre location. For me and one other person, it thought that the target was inside Markarth (but still seemingly at the same map coordinates as Mount Anthor); for another person, it was inside the EEC. Trying the console command MOVETOQT BQ04 simply caused the game to crash.
It’s riddled with mods, but I’ve attached a saved game, in case it’s useful.