Hi James,
Thank you for your reply, Some hours ago I called to Tech-Support, and Luke Stone pointed me out that I was using the Track&trace module v.1.6.7 along with OEE Module v.1.6.6. and suggested me to upgrade OEE to v.1.6.7
I did that and now the problem is gone. All dropdowns and WO tables get populated correctly.
Thanks a lot for your help!