Almost had it a good few years ago in a MERC 814 (7.5t)
On way up to Stirling early morning felt really bad vibes of wheel, pulled in to a Ats , guy could turn nuts with hand !
Now I had done a visual inspection in the morning but figured i would still get crap for it , turns out as well as that we had a brake pipe cut (not right thru but enough it caused the pipe to burst not long later) fitter pulled of pipe and could clearly see cut nice n clean then the wear,
Bosses recon it was ex driver recently sacked , cops called they tried forensics but was a waste of time on a commercial,
Cops did a interview but couldn’t prove anything, but nothing else happened .
Yes I’ve had two come off, mind they were still attached to the rear trailer axle 
happy days.