Missing computer after upgrade 2.6

After migrate from 2.6-RC to 2.6, some computer aren't display in the web. the record still in the db, and are updated but no are displayed.
The 'hidden' computers have different OS (Ubuntu, Debian, WindowsXP and Windows10), the agent does not seem to be the problem, since they have unix_agent, windows_agent and injector_pl.

Thanks for your help (and sorrry for my english)
Raydel