How to fix (2013 update)
I've tried the bugged saved game file I initially posted in my question with the current latest versions of the official patch, Unofficial Skyrim Patch (USKP) and Skyrim Script Extender (SKSE), and the saved game is now Aspect of Peryite-free.
I've configured SKSE to use its ClearInvalidRegistrations
console command on every saved game load, which removes invalid scripts left running by uninstalled mods. This feature was introduced in v1.6.7 of SKSE:
add console command ClearInvalidRegistrations
to remove invalid
OnUpdate() registrations
This prevents orphaned OnUpdate() events and
the resulting bloated/broken saves when removing certain mods. When
applied to an already bloated save, it will stop growing further and
instead shrink over time as the game processes all queued events. This
may take hours depending on the amount of bloat.
To execute automatically after each reload, add this to \Data\SKSE\skse.ini
:
[General]
ClearInvalidRegistrations=1
According* to a developer of the Unofficial Skyrim Patch (USKP), the underlying cause is because DA13 ('The Only Cure' quest) is never stopped.
A possible fix* for this:
In the meantime, load an affected save, then type stopquest DA13
into the console. That ought to put an end to that. Plus it’ll free up some unnecessarily leftover alias memory.
BTW, don’t use the console command on a save not bothered by it. Even though it may appear benign, console commands can have negative consequences you don’t know about.
If this doesn't work or if you experience issues like: NPCs not responding properly to conversation (not reply to you when you choose a certain conversation path - leaving you stuck), merchants not opening the buy/sell window, horses that can't be ridden, and other interaction issues, then the save game is most likely corrupted. Try the SKSE ClearInvalidRegistrations
console command fix I've posted above, instead.
To prevent this from happening in the PC, get the latest version of the Unofficial Skyrim Patch. This has been fixed since version 1.1 of the USKP:
"The Only Cure" (DA13) was never stopped which would lead to the Aspect of Peryite randomly initiating conversation and being unable to exit.
* This info is from the old USKP bug tracker page at 16bugs.com, which is now not viewable. The new USKP bug tracker report page of this bug is at afkmods.iguanadons.net.
There is a known bug with this quest where the perk that allows you to harvest blood is not properly added when the quest is given.
Since you don't have access to the console on the XBOX version, you can't use that to fix this. Therefore, you must reload to an earlier save (before the quest was assigned) and hope it works the second time round.
It won't resolve your issue in this case (due to the specific way the quest is set up), but you might also consider updating the game; Bethesda has been much better about patching bugs in Skyrim than they were in Oblivion. Preventative measures can't hurt!
(Though, for what it's worth, I just got hit with this bug myself, despite an up-to-date version + the unofficial skyrim patch)
Best Answer
Yes, this is a known bug. This is caused by a scripting error within the game. There are several things you can try, in order to fix this issue.
Try exiting, and re-entering the glade to see if it fixes.
Try fast traveling to a far off location, then travelling back into the area, and see if it works.
If none of this works, then there is a more direct approach to get around this.
Solution: Use the console commands: 'player.additem xx0191b7 7' (to add the Canticle Barks) then: 'setstage DLC1VQ06 30' (next stage of the quest), then just continue the quest, where "xx" is the load order for the DLC Dawnguard (typically 02).
This is a guaranteed fix, and doing this should allow you to continue your game and circumvent the bug.
Good luck!
Edit: In regards to "not wanting to add them to your inventory" that is the only option, if the other things do not work as mentioned above. It's the only known solution to the problem. However, I am not 100% sure, but it is a possibility that one of the unofficial patches or bug fix mods might have fixed this issue at some point, that is a high possibility. There are a few unofficial mods that are said to fix many known bugs, and many issues, errors, and scripting issues. There is a strong possibility that one of these mods would fix this issue you are encountering. For example, unofficial skyrim patch, or misc fixes patch, both found on Nexus Mods.
Edit 2: I also just noticed, since it's a Dawnguard quest, the "Dawnguard Unofficial Patch" would be another patch mod to look into as well.
Edit 3: I just did several searches for mods on Google, Nexus Mods, and so forth. I also did several searches through the Unofficial Dawnguard Patch, and it doesn't seem like anyone has tackled the scripting issues for this quest via any known mods. So the only option it would seem is to use the command console, to do as was described above.
Edit 4: I might have a different solution. I did some further digging, and found this: http://www.uesp.net/wiki/Skyrim_talk:Unseen_Visions Specifically the excerpt here: "Simply put, I grabbed the draw knife and activated the tree only to go into 3rd person view and watch myself do nothing for about 4 seconds. Looked up this page and tried reloading and deactivating my mods as it suggested and nothing worked. Spent 15 minutes on google only to find the solution mentioned once. That being that its waiting for you to preform a resorse gathering animation such as chopping wood, after using tcl consol command to escape the cave I tried this and it worked. immidately after I finished my wood chopin I recived the bark and a quest update. — Unsigned comment by 99.235.239.235 (talk) at 04:30 on 14 August 2012 " Below that, two different people confirm this fix worked. This might be a way to get a solution, and not have to "add item" which you said you would rather not do. Try it out, and let me know if it worked.