Late last year I lost a Green #1 HB flexifix in the lost arrow wall, had a post about it lower down the page. As for proving it, if we are talking about the same cam I can show you rest of rack with that one missing. ?
This was in “First Route” I hadnt seen it there a week or 2 ago when we climbed there, There is an old cam stuck in the climb “Lost Arrow” I remember we spoke on the forum cos I lost a cam at the base.. The one about 4-5m up Lost Arrow is still there..