I did that quest about two days ago, it ran fine, short of logging out and restarting it, I don't know what to suggest.

thanks guys. I appreciate the responses. I've been logged out overnight - let's see what happens.

I have done the Fit to rule !

This quest is bugged for me as well. This is my third time playing through this particular content, and :

I am attempting to finish the quest "Eldenroot Orrery", but every time, as it is supposed to happen, when no matter how many times I press the 'activate" button, either nothing happens, or I get the "item not ready" message. I have done this quest twice before, so I am rather confident that it's a bug, not something that I am doing wrong.

I have tried logging in and out multiple times and standing in various different locations; even disabled my pet; but nothing seems to work. I have even abandoned the quest and started it over, but still the same result.
PLEASE HELP urgently so that I can continue the main quest in Greenshade. Thank you.

Ah, so I'm not the only one... NUMEROUS quests are bugged after DB dropped. Have had to abandon the "Keeper of Bones" quest because I could never get the 'horn of niranon' to activate no matter how many different places I tried... also kept getting the "item not ready" error. Then had another in Reaper's March, the one where you have to collect water in a container, but again, the pressing 'E' to activate and nothing would happen... again "item not ready" but finally, out of no where, after another player approached, it actually worked... so that's one I was able to finish after a LOT of angst and even a /bug report. This was NEVER like this prior to DB, as I've done these quests many, many times with alts and never had this problem... then suddenly after DB all sorts of these bugs involving specific 'activation' sequences.

Also, I bugged out in Reaper's March Thizzrini Arena quests... the one for the Swordmaster Championship... I wiped out the champion in apparent record time, the problem was, it never registered as defeating the champion... so now it's bugged with the spears coming up and down from the floor and no way to progress. I've abandoned and reacquired the quest, only to realize that the game remembers where you left off, so I talk to the champion and go into the first arena but it immediately tells me to leave and talk to the champion again, I do and then we're heading back to the main arena... only to find myself back with no champion and the spears coming up and down from the floor. *sigh*

@ZOS_JessicaFolsom Has there been a noticeable reporting of /bugs with these type of quests since DB's launch? I've already encountered a couple of them involving not being able to 'activate' items in various quests which were never a problem before in all the times I've run those quests.

If you can't finish this quest, try to use Rahjin's Mantle from inventory (Quest section), it worked for me (https://forums.elderscrollsonline.com/en/discussion/269575/game-breaking-orrery-bug)