Beta just went up and spells are not changed.
 

Resisted 20 of 20 roots and 20 of 20 snares on myself with 81 mr (level 50 wiz)

Turn off hacks then try.

Yeah, that's a little extreme. I would think with that much MR you would at least land 2 or 3.

My druid has 40-45 MR and i resisted 20/20 snares on myself.

Could it be possible that when casting spells on yourself the game uses a different algorithm?

Recently(after the new patch was updated) I was snared(clinging darkness) and rooted several times by players both higher and lower than me and it stuck most of the time. Whenever I try casting root on myself though with 30mr I resists nearly 80-90% of the time.