I checked lab cases and found this:
Here is quote from documentation:
“1.1.1.1 Remote PowerShell Configuration Privileges
... By default the Mailbox Import Export role isn't assigned to user. Hence this role has to be explicitly assigned to the user. This role is necessary for performing the following tasks:
Steps to Assign the Role
To add this role to user, execute the power shell command
New-ManagementRoleAssignment -Role "Mailbox Import Export" -User Administrator
at the Exchange Management Shell prompt.”
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From another lab case:
Exchange server adds roles with visible name (not username). Example “Mailbox Import Export_Visible Name”
Rename visible name in active directory, than delete role, add role and all works fine. Exchange GRE now starting more faster and do not ask the “username password”, when logging on with dataprotector username.
Rename visible name in active directory, than delete role, add role and all works fine. Exchange GRE now starting more faster and do not ask the “username password”, when logging on with dataprotector username.
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All of these were reported for DP 8.0, so, I am not sure if they would be valid in your case