If both Shinobaron(ess) Shades have been banished, and were properly Ritual Summoned, during the next standby phase the option appears to activate their effects to summon themselves, however, if one is summoned back, the other one is never allow to activate, essentially you can only bring back either one of the two, never both. Also, sometimes, Shinobaroness Shade will activate while banished (and is the only banished effect I will be activating) and she will resolve without summoning herself. The bug seems almost random and is hard to test for, but it seems that it will mainly occur if she is summoned through the effect of The Himorogi Where Stars Align.
Bug reproduction steps
Properly summon both of the Shinobaron(ess) Shades and then banish both of them (easiest through Shinobird Calling). During the next standby phase, only one will be able to be summoned. As for the bug that stops Shinobaroness Shade from being summoned at all, I have no idea.
Screenshot OR error code
Both Shinobaron(ess)es Shades should be able to be summoned back during the standby phase and Shinobaroness Shade should be able to be summoned back if she was properly ritual summoned
What OS are you using
Try this again