[Update]
I found the following case exactly the same as mine but my problem still exists after I tried cleaning up "Purchase update history clean up".
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I have Purchase Orders with stock received waiting for invoicing like below.
When I try to invoice them, system crashed and they are locked like below.
I encountered this many years ago and the system admin of my company solved it however he left the company and no one know how to deal with it.
Anyone knows how I can release them?
Thank you!