I once couldn't get a soul from a specific, generic, dragon even after I repeatedly used "resurrect" on them and kept reloading. I just moved on and later killed the dragon who spawned in their place as revenge. The new dragon that replaced the old one gave a soul.
I don't think console commands will help, unless they would specifically give you a dragon soul. Resurrecting them or instantly killing them don't seem to help.
Hopefully it's just one dragon that is causing you grief and not all dragons. If it's one specific dragon at a dragon lair, just come back later if you want to have their location "cleared".
Yeah, that happened to me yesterday. Killed a dragon, but he didn't give his soul. Perhaps he was just faking his death.
But it's no big deal to me. Only happens once in a good while and there are plenty of dragons I've encountered out there, yet to give up their souls.
Make sure all the patches and unofficial patches are applied in order? That was my problem.
Sometimes it can be glitchy as well. I've had it happen where I kill a dragon and it isn't even lootable at first. Next time I fast travel, said dragon swoops down from the sky and dies instantly, allowing me to loot/absorb. This game is funny like that
This was an issue that had been patched, can't remember which patch.
After the patches, when ever I kill a dragon from a dragon lair that I have already been to and killed the previous dragon, I get no soul. I can't confirm this but I think it may have been designed like this to prevent people from re-visiting dragon lairs to kill re-spawned dragons and stock up dragon souls.
It can happen on respawned dragons i believe - the guardian ones of word walls.
Once you've absorbed it once, that's it despite respawning...