It probably didn't fail, it wetted out which is when the outside material bonded to the membrane become sodden.and the membrane then can't breath as its essentially blocked.
That or if the membrane is dirty it can't breath effectively enough and you end you wet again.
The membrane then can't breath, what is making you actually wet is your sweat condensation on the inside!
Used to work with gortex in a mountaineering shop when i was younger so know a good bit about it.
Reproof wise id use nickwax green, then purple. Once it's on and if your garment allows it, tumble dry it and it activates the DWP layer you have just washed onto the material.
Granger stuff is also good.