Domain Mapping - Cannot logout from mapped subsite

When Administration Mapping is set to "Mapped domain" in Domain Mapping network settings, and Cross-domain autologin is also enabled, we cannot logout of a domain mapped subsite.

We can logout of the main site or the network admin, but remain logged into the mapped subsite.

When Cross-domain autologin is disabled (with Administration Mapping still set to "Mapped domain"), we can log in and out of all sites just fine.