Why MCP Memory Servers Show 'Connected' But Don't Share Data Across Editors

Developers using both Cursor and Claude Code with a shared MCP memory server may find that notes saved in one editor are invisible to the other, despite both clients reporting a healthy connection. The root cause is that a successful connection only confirms the transport layer is working, not that both clients are authenticated to the same account or backend store. An analysis of six persistent memory systems found that the most common failure mode is two clients connecting to different accounts or data stores without triggering any error. Some systems, like Cognee, also offer distinct architecture modes — standalone versus API-connected — where only the latter enables cross-client sharing. The consistent fix across all reviewed tools is ensuring every client uses the same account credentials and points to the same backend, rather than assuming a connected status implies shared memory.