On my current character I am trying to collect the 8 dragon priest masks and on the hunt for the final one. As I've been playing this character for a while I have explored a lot of the map so its hard to really plan where my search will continue. The easy solution is to hunt down word walls and eventually I should come across the final priest, so off I popped to High Hrothgar to get a word wall location. I get sent to Arcwind Point (I think thats what its called) but I have already been there and activated the word wall. When I got up to the word wall the word is glowing but nothing happens when I approach it and I can't complete the Miscellaneous quest to find the source of power. Is this just a bug or have I run out of word walls? I know there are some in places that are inaccessible unless you do certain quest lines and I guess the Greybeards would never send you there.
On another note, are named dragon priests with masks always present whatever your level? Or could I have cleared a dungeon at a low level and only come across a different levelled draugh?