@DC_10584147 As I answered you in a older thread
just to be sure >D
I can see that there are some custom ext. actions.
It seams that the actionConfiguration xml file customActionModel.xml contains wrong definition for the Task assistant.
Check the OOTB actionModel definition and add the correct row to the customActionModel.
There can be naming change or something else between Windchill versions.
similar think happened to me if I just copy the customActionModel file from previous version to new one without any check, Some actions were missing because they change a internal name used in the XML.
here is example how the Task assistant definition looks like


PetrH