Outlook Search Broken & Incomplete Email Display

Disclaimer: I will answer you in English based on your previous message. As a friendly suggestion, posting in Chinese (Traditional) may help your question reach a wider audience and increase the chances of receiving assistance from other community members.

Dear William Li,

Thank you for reaching out. I tested this in my own environment, using both the new Outlook desktop app and Outlook on the web, and search returned results as expected there. Since you see the same behavior on different browsers and computers, the cause may be specific to your account or mailbox rather than the browser or device. To narrow this down, could you please confirm the following:

1. When you search, what exactly happens (for example, "no results", an error message, or it keeps loading)? Does it happen with every search term?
2. Does the issue also occur in the Outlook mobile app or the Outlook desktop app?
3. If this is a work or school account, do other users in your organization see the same behavior?
4. Does the incomplete display happen in the Inbox, in search results, or both? Please take a screenshot and share it with me.

With the mailbox search error, I find several workarounds that you can double-check it first: 

 1.Use filters to narrow your search and show older email messages: 

2. Outlook search returns incomplete results, or search can't find older emails:

For reference: Troubleshooting Outlook search issues

Besides that, I find an article related to verify and rebuild the search index on the server side in Exchange Online: Rebuild search index of a mailbox in Exchange Online

Additionally, there is an idea to fix search issues by rebuilding your Instant Search catalog, see more details in here: Fix search issues by rebuilding your Instant Search catalog

I hope this information can help you to solve this error with the mailbox search. If it still does not work, please let me know.

Thank you very much for your time and your cooperation.