It could be mods maybe check the Nexus or Workshop comments for the ones you use and see if theres any mention of a similar thing happening, you try and and start The Way of the Voice with the command -
setstage MQ105 10
You should hear the Greybeards calling you on your way back to Whiterun after killing the dragon. If you didn't another thing to try is before going to kill the dragon use the command -
coc highhrothgar
That will teleport you to High Horothgar, find the four Greybeards and see if their working (not stuck in the ground or frozen) if ther not one at a time open the console click on them and use the command -
recycleactor
That should fix them and you can go back to Whiterun and try killing the dragon again (and walk back to Whiterun to make sure their voice triggers).