I went to Arnegeir of the Greybeards, who gave me the radiant quest to go find a word in a shout. He sent me to Arcwind Point, an open-air location South and ever so slightly east of High Hrothgar, and just a bit west of Autumnwatch Tower. Walking up to the word wall, I receive the shout as normal, and can use it as normal, but the quest does not end. The marker just keeps pointing at the word wall. I headed back to Arnegeir, and he won't give me the quest to find another word, so the quest is still active, but I can't complete it because I already have the word. I reloaded my save and I have tried this three times to no avail.
The word in question was ''Health", the third word of the "Drain Vitality" shout after the words "Stamina" and "Magicka".