Thank you

I see in your explanation that "advantage" allows two rolls?
if that's true then I very misunderstood the mechanic. this is my first 5e

Still seems the statistic is slightly off. let see...

if I have a 25% chance of missing and two rolls
by my maths that is 6.25% chance to miss (anyone good with maths?)

so a 93.75% chance to hit?
that is a lot closer to the displayed 96%

anything else that could be coming into play?