It might be because there is some exception happens when GS_CM/Doc Tree view gets opened and this exception is not captured which causes the problem on the lateron operation(as you click on the screen).
Have you checked if there is any records ST22 or SM21 generated when you click 'advanced' button?
Maybe you can compare the whole logic when GS_CM/Doc is opened between two systems (if you have another system on which the issue doens't happen).
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Additonally, the issue happens when you create an interaction and then navigate to Attachment assignment block? Are you creating an 'interaction record' in IC role? How do you navigate to 'attachment' assignment block? have you add this assignment block to 'ICCMP_BTSHEAD/BTSHeader' yourself?
Best Regards, Corrine