are 2 saves prior to the described issue.
1st save : Bring ingredients to Kesh. Inhale the smoke to trigger the introducing dialogue with Peryite. From this very first interview you can exit dialogue by using the TAB key with the impossibility to recover controls, and probably no option to trigger again this quest if you manage to fix it (note : the "Peryite shader" seems to be locked as well). Processing normally by clicking on the dialogue options seems to be flawless and allows the quest to go on.
2nd save : Orchendor freshly killed. Grab the key to the elevator on his corpse and exit to Tamriel. Go back to Peryite shrine by fast-travel and you'll be in the exact same circumstances as the original save I provided. The issue is exactly the same...
This issue may happen in every dialogue where the player controls are not restored when exiting 'roughly' a conversation (probably most other daedra dialogues). I may find the scripts that are 'trapping' the player if you want to go further. Just tell me which string/command I should be looking for. Anyway, the best way to solve this issue may be to disable the option to end the dialogue earlier than expected by the game. I don't know how to implement this.