I am having the same problem as the OP. I have 3 unspent Dragon Souls and have been collecting Shouts for a while now that I cannot unlock. The only Shouts I can actually use are the ones given to me by the Graybeards (and yes I did complete the Graybeard quest-chain).
I have 3 shouts that need to be unlocked; "Become Ethereal (Word learned is "Fade")", "Ice Form (Word learned is "Ice")", and "Kyne's Peace (Word learned is "Kyne")". "Kyne's Peace" was learned before I received any Dragon Souls at all, and the other two were learned after I had received Souls, so it is not a problem of the order in which souls/shouts are gained.
So here is what I do step by step:
- Open up the player menu (Tab on the PC)
- Select Magic
- Select the Shouts tab
[indent]In the lower-right hand corner of the screen the game tells me I have "3 Dragon Souls"[/indent]
- Highlight a grayed-out shout that I would like to activate
- Press "R" - Game says this button "Unlocks" shouts
[indent]Nothing happens[/indent]
- Double-click the Shout to activate
[indent]Error pops up that says "Dragon souls are required to unlock shouts."[/indent]
- Press "Okay" twice (because the error pops up again directly after hitting "Okay"
- Nothing happens, no Dragon souls are spent, no Shouts are unlocked.
I did in fact remap my "Sheathe weapon" button to a mouse button, but pressing the mouse button also does nothing.