On-Call Scheduling, Manage Shift: members not showing

[Flavio4]

Hello,

I have a simple schedule for a group, with only one roster of 5 members, rotating weekly.

I need to simply deal with replacements (absences): the person to be absent will (offline) agree with another member of the roster the remplacement, and manually make an exception in the shift, switching the rotas in the On-Call schedule calendar.

As far as I understand and expect (from SNow doc, videos, etc.) this should be possible in the following way:

- the member of the roster will display the schedule calendar, select the target shif, "Manage Shift", Action: "Provide coverage", select the target Start&End, select the member providing the coverage.

This works fine if the account has the role "admin".

Unfortunately, an account with role "rota_manager" or "rota_admin" or both (without the "admin" role) is not able to see all the members of the roster to select who will replace them.
Only one member is displayed, always de same. Clicking on the Member dropdown list, will show "No matches found", although the roster displayed in Rosters is correct and contains 5 members.

Please check&compare the two screenshots.

Is it a problem of access rights to the group?
How to fix it?
 

Thank you
Flavio