It's well known.
And highly variable. The cargo cover will stick when it's cold out, when it's damp out, and depending on if you have the carpet on the bottom side of the cover.
If the tailgate is down, it will fully lift every time. If that is, it's not too cold and the oil in the gas struts is fluid.
I've put stronger struts on but that's not really a winning solution. It takes far more effort to close the cover.