Occasionally, when you cast Knit Flesh, you can get a "Resist!" proc and the heal-over-time portion doesn't trigger. It definitely seems to be linked to your actual Magic Resistance stat; I grabbed Ancestral Body Paint as a test and sure enough it started happening even more often. The small initial heal and debuff never fail to trigger. I have also yet to see any other self-buffs get resisted in this way, but I haven't looked extensively. This was already happening as of 1.07, but I hadn't figured out the cause at the time.