The temp fix for now is:
After you deploy last droid at Sarlac Pit and it finishes, it tells you to take the canister. At that point, simply open your map and change the instance. After you do, the sarlac will spit the canister out and it will be available to pick up.
It's incredibly frustrating, I know. I completed it on four characters so far, and the bug is the same. Thankfully, for now, so it the temp fix.
Good luck!