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The spaces tab not appears on site admin and to click to back on 'Settings, return to main application' (Gear icon) shows the error: 'The webpage cannot be found - HTTP 404 Not Found'
Licenses issue, checking the sharing licenses configuration, we detected it was defined on port :8080 and not on :80 (empty port) as the ALM URL on octane.yml file in the server, in order to get the licenses from ALM 12.55.
We set the shared licenses parameters correctly, and restart the Octane service. After that the spaces tab appears as expected and the gear icon works as expected.