I cannot select part reference planes inside the assemble command - why?
There is a known issue in ST9 with the Assemble command where part reference
planes cannot be selected if the perspective view is turned on. If you assemble
a part then display the reference planes of the placement part and cannot
select those reference planes you will need to turn off the perspective view.
The issue is resolved in ST10.
Notes and References
OS Version: 764SP1