Symptoms

When loading a Display Manager configuration, only 2 displays are restored.

Cause

A lot of browsers by default only allow 1 popup window. The others are blocked by the built-in pop-up blocker of the browser.

Resolution

Check in the Workspace tab of your browser whether an icon (often a small red one) indicates whether popups were blocked. If so, click on it and adjust the setting to always allow all pop-ups from the Workspace.