i guess i am now experiencing the same thing. my truck was waxed with collinite 845 about 4-5 weeks ago and it's been washed....um.... 3-4 times in that period
and after the wash, the roof and hood have no beading and no real sheeting either.
I use the Meg's GC wash/shampoo.
I've noticed that exact thing with 845 with all different brands of washes. Odd, because I'd been a long-time user of 845
with no problems. All the sudden, I start to notice during washes that the hood and roof of my truck are flat
while the sides are still beading like crazy.
My guess was that direct heat, from both the Sun and the engine, was quickly breaking down the protection.
That combined with heavier accumulation of road contaminants and random debris that settles on the vertical surfaces
was causing premature failure. But, then, that should be true of any wax or sealant.
I've since switched to 476s and have gotten better wear.....plus, the look of 476s on my white truck is truly incredible.
REALLY impressed with it.