Double check and listen if the hood clicks when you fit it to the lens.
May be a situation with the spring isn't in place and it's simply not locking onto your lens.
If that isn't the case, check out your handling techniques, as you may be inadvertently taking the hood off, so to speak.
Thanks, but definitely no problem here on that score...it's clicking in just fine. I just get so absorbed in my work I take minimal notice of my gear, even in busy, tight packed events where the cameras, lenses & flashes get knocked around almost constantly. Other than my run-away EW-88C hood, in general the gear handles the extremes of job pressure perfectly well, the most vulnerable items being the cables running from flash to external batteries getting snagged and modifiers like Stofens or Gary Fong getting dislodged and lost. I can't recall the large hood on my old optically inferior 24-70 f/2.8 MkI ever falling off.
Not to worry, I'll find a fix.
Yes, the release button has a light touch, as does the 70-200 II's.
My 70-200 f/2.8II hood release button needs a much heavier touch than the 24-70 f/2.8II under discussion.
I suspect mine is merely a production line anomaly.