I figured this one out myself. So I'd been experimenting with smodeNet, joined a session on another pc, then decided to stop using smodeNet. After disabling smodeNet, the session was still locked to the project on the other PC. And since the Network menu isn't visible when smodeNet is disabled, I didn't think to look for network related issues. If smodeNet isn't enabled, doesn't it make more sense to automatically leave other sessions?