SSMS IntelliSense Blank While Queries Still Run
When SSMS stops suggesting table and column names but still runs queries, check the window's connection, the local cache and the account's visibility.
Typing a table name produces no suggestion, yet the same window happily runs SELECT statements. That combination is the clue: the connection works, but the editor's completion state does not. SSMS keeps its own cache and its own idea of which database and account the window uses. Treat that state as separate from the tunnel before changing any network setting.
The Window Has Its Own Connection State
Each query window carries a connection, a database and an authorization context. Object Explorer can be connected to a different server or database, and another tab can be running as another account. Confirm the affected window's own status before comparing it with anything else. A window opened before the VPN came up can also be bound to a connection that no longer exists, so its status matters more than the title bar suggests.
A VPN interruption can leave that window disconnected while the application still looks alive. Reconnect through the normal SSMS workflow, then confirm the database selector shows the database you expect.
Force the Local Cache to Rebuild
Microsoft's IntelliSense troubleshooting guide documents the supported refresh: Edit → IntelliSense → Refresh Local Cache, or Ctrl+Shift+R. Use it after confirming the connection, particularly when objects changed while the window stayed open. The refresh rebuilds a local list; it cannot restore a network path that disappeared.
Also confirm that IntelliSense is enabled for the editor and that the installed SSMS version supports the statement you are writing. Completion behavior differs across versions and does not cover every product or script form. If the shortcut does nothing, treat that as an editor-state symptom rather than a VPN symptom. A menu item that stays greyed out and a shortcut swallowed by another key binding are both editor facts worth recording before the tunnel is blamed.
Missing Names Can Be Permissions
Completion lists only suggest objects the connected account can see. A script copied from a colleague can therefore reference names that your session is not permitted to resolve. Compare the intended account's visibility instead of an administrator's unrelated session. If a name is missing because of permission, fixing the editor will not make it appear.
Ask the database owner for the minimum permission the task needs, and keep that grant specific. Broad administrative rights granted to populate a suggestion list trade a small convenience for a large exposure.
Decide Which Failure You Actually Have
Two failures look similar from the keyboard and need different owners. If ordinary statements in the same window also fail, investigate name resolution, transport and authentication for that connection. If statements run and only suggestions are missing, the evidence belongs to the editor. Write down which of the two you saw, because the two reports go to different teams and a mixed description delays both.
Keep the installed SSMS version, the selected database, the account and one small non-secret example for the tooling report. A recording or a list of the exact names that fail helps more than the phrase IntelliSense is broken. Then retry after the cache refresh and after a reconnect, because those two actions separate most cases.