Upon an invalid grandpa justification (be it malicious or accidental) the enclave stops importing new blocks (printing error of the same block all the time).

Substrate has changed it's logic there already, an update of justifications.rs is necessary, as well as further investigation.

Check out substrate code here: https://github.com/paritytech/substrate/blob/master/primitives/finality-grandpa/src/lib.rs