Hi Andreas
in standard it's possible to insert another workcenter in confirmation. In this case the original workcenter is displayed but you insert the new workcenter in another field.
In Co11N it depends if you add the relevant screen in OPK= profil, in CO11 you see the field in tab additional data.
If this was done one time, this changed workcenter is proposed for new confirmations in standard. Maybe this happend in your case? If yes modification from note 666015 could help, this modification will lead to the behavoir that always the planned workcenter is proposed.
Hope this helps.
BR Sabine