Question
In Microsoft Loop, sharing / Inviting members comes up blank with company staff contacts missing
Why the picker goes blank
| Behind‑the‑scenes step | What breaks when the user lacks a mailbox |
|---|---|
| Loop asks Microsoft Graph for a list of people as you type | The request is scoped to the user’s /me/mailboxSettings resource. Without a cloud mailbox that endpoint returns 403 / MailboxNotEnabledForRESTAPI so the query is aborted. |
| Graph call fails → UI shows “no results” | Loop doesn’t display the raw error; it simply returns an empty array to the people‑picker, so you see no names. |
| Invitation API call is gated on mailbox | Even if you could paste a UPN manually, the final AddMember call also checks that the inviter has a mailbox, so it would fail later with “We couldn’t add members”. |
Microsoft’s own admin guidance phrases it this way:
“To utilize **all Loop app features, including workspace sharing and @mentions, it’s necessary for all users to have an Exchange Online mailbox.” Microsoft Learn
The same prerequisite is repeated in the public “Get started with Microsoft Loop” support article.
What you’ll observe in practice
| Scenario | Result in “Add members” search |
|---|---|
| Inviter has no mailbox | Nothing resolves; spinner or blank list. |
| Inviter has mailbox, invitee does not | Name does appear, but clicking Add shows “We couldn’t add members” because back‑end validation spots the invitee’s missing mailbox. |
| Both have mailboxes | Name resolves instantly; invite succeeds. |
|
|