Do you mean that his mystery doesn't grant the 2nd standard attack to midnight blade even if mb has anbu special tactics selected as a talent?

Are you sure you weren't selected by a buff removal chase/standard/mystery? Because his additional standard attack works like bee sst one,so if mb suffers a buff removal it gets cleared.

Hi! Just as Scarlettblue said, there are two parts to Shin [Edo Tensei]'s mystery. One part grant's one ally you select to have all Debuffs removed and reducing mystery cooldown by 1. The second part granting an additional attack only works if the selected unit is marked as Anbu. If a Buff removal is used by opponent on the same selected target, it does negates the additional attack.

Also, to help us better, please use the bug/support section for any reports related to bugs. Thank you. You can find it here.

Edit: Courtesy to Zathroth as well for pointing out a confusion in sentence.