One may question, “Many accomplished masters have attained extraordinary realization. Why would they still encounter obstacles or become ill?”
There are two possibilities. One of them can be explained by way of the Twelve Nidanas. Accomplished practitioners may have eradicated all defilements in this life, but they were once ordinary beings in the past. Even Shakyamuni Buddha was an ordinary being before attaining Buddhahood, not to mention the lesser known practitioners. As an ordinary being, one cannot but commit karma and karma is infallible. Consequently, even accomplished masters must still go through suffering in this life due to some distant causes not yet resolved. Nonetheless, this will be the last time they would ever experience suffering again in their cyclic existence since primordial time.
~ Depicted from Luminous Wisdom Book Series 1