How is the copying process being run? It seems perhaps sensible that you are failing to take out a lock if multiple processes are trying to do so at the same time. Is your desired behavior to not use locking for the copy process?

https://docs.intersystems.com/irisforhealth20243/csp/docbook/DocBook.UI.Page.cls?KEY=GCOS_lockbasics#GCOS_lockbasics_sqlobj