I'm having the same issues. I thought perhaps the word walls bugged (95% of them won't work, just a static sound when near them) because I installed the alternate start mod where it puts you up to the progress having your first shout the moment you start, without looking at a wall or slaying a dragon. I disabled the mod but nearly all the walls are still broken. I came across 1 wall that worked and I was amazed (I think it was the wall you come across at the start of the dawnguard dlc when you save the vampire daughter. Anyway, I'm thinking of restarting (which sucks, done the quests a few times now, just breaks the fun and immersion) but this time I'll do it with limited gameplay mods (no alternate start). I haven't spoken to the graybeards yet, so I'm going to try that before trying a word wall again, but from what I've read this is a problem present in vanilla w/o mods. Using all the unofficial fixes, completely up the date using the legendary edition from steam. It's annoying this is such a sporadic issue that's hard to identify any damn cause; now a good chuck on the content (shouts) is out for me because of a bug... sweet.
