» Fri May 27, 2011 10:14 am
The UESP Wiki has http://www.uesp.net/wiki/Shivering:The_Museum_of_Oddities to say on the subject in the "bugs" section on the quest:
"Sheogorath-Shaped Amber appears randomly and only in non-respawning containers. If you are unlucky, you may never find it and thus be unable to complete the quest. The Unofficial Shivering Isles patch adds a small percentage of finding it on Elder Gnarls however, which do respawn. "