According to the wiki scan + cloak helps hacking success.
I'm level 47 with 276 scan, 116 cloak and fail a large portion of my hacks against people with barely any sensors/cloaking (with that much scan, i can see almost everything they have equipped)
Is there another stupid code similar to the deck-space/damage cap limit but for hacking?

Depends on what you mean by fail. There are two kinds, the kind where you get a badge (this means your hack passed, they just had nothing to hack) or no badge (your hack failed).

And yes, there is lower protection so you have less of a cache to get good stuff from levels lower than you.