Select ‘Revise post’ for a pending queued post (that isn’t claimed), don’t select ‘Send PM’ but cancel instead. The text now says ‘You’ve claimed this item and can review it.’ and no x button is next to the text so can’t be unclaimed.
Also, shouldn’t the post return to being unclaimed if prior to selecting ‘Revise post’ the post wasn’t claimed and you’ve opted to cancel when on ‘Revise post’?
Installed version: 3.5.0.beta7-dev (1f2efa7954)