The Stash product added support for Crowd a while back, but continues to not have Crowd's SSO support.

Please communicate to the Stash team that having an Atlassian Enterprise-grade product (i.e. Stash) that doesn't log into Enterprise-grade features of other Atlassian products (i.e. Crowd) is frustrating and, dare I say, second-rate. It essentially nullifies the SSO benefit for a portion of the Atlassian portfolio and makes it unclear how well Atlassian understands its own products.

Thanks for all the hard work, guys!