The issue of self-reflection being available for some subjects but not others in 360 projects can be due to several factors. Key points to check are:

1. Ensure that the self-reflection option is turned on in the project participant options.
2. Verify that participants are not marked as 'Done' or completed, as participants in this state cannot complete self-evaluations.
3. If managers need to see self-reflection status, ensure either “Managers can access their subjects’ reports” or “Manager approves subject's reports” is enabled, otherwise the self-reflection column will not be visible to managers.
4. There may be some delay due to caching of the project configuration that can temporarily prevent changes from taking effect.
5. Partial or incomplete self-evaluation responses (e.g., participant did not submit at the end) might not count as finished, causing them not to appear correctly.
6. Recent feature flipper changes or bugs could cause self-evaluations to show as 'This evaluation can no longer be completed.' If this appears suddenly, filing a pulse for engineering investigation is advised.

In summary, it is important to check participant status, project settings for self-reflection visibility, and ensure there are no partial or unfinished self-evaluation responses. If everything appears correct but the problem persists, it is recommended to file a support ticket for deeper troubleshooting.

These points reflect known issues and recommended checks documented from internal support pages.