Hi Arista
Thank you for reaching out to the Q&A Forum.
You mentioned that you’ve already tried several methods. Aside from creating a new Outlook profile and checking rules, based on my research and understanding, I have a few additional recommendations. If you have not tried these yet, I hope they will be helpful.
Check "Filter" and "View" Settings:
The "Pop up and disappear" behavior usually happens when the view is set to "Unread" or filtered. When an email arrives, it is briefly visible; once Outlook marks it as "Read" (often within seconds), it disappears from the view because it no longer meets the criteria.
- In Outlook, go to the View tab > Click Reset View to clear any custom filters. Please ensure your filter (located above the email list on the right) is set to "All" and not "Unread".
For your information, you can see: Items disappear or are not visible in an Outlook folder - Outlook | Microsoft Learn
Check Focused Inbox
If Focused Inbox is enabled, emails might be "popping up" but are actually landing in the "Other" tab, making it seem like they disappeared from your main list.
- Look at the top of your email list. Do you see two tabs labeled Focused and Other? Check the Other tab to see if your missing emails are there.
- If you prefer a single inbox, go to the View tab and click Show Focused Inbox to turn it off.
Run Outlook in Safe Mode
Since you mentioned the new profile did not fix the issue, we need to rule out interference from third-party Add-ins, that might be moving or hiding emails as they arrive. Here is detail guidance you can try: Open Outlook in safe mode - Microsoft Support
Check the "Sync Issues" Folder
Since you mentioned the Desktop is not syncing correctly with Webmail, Outlook creates logs that explain exactly why the sync does not work. These logs may locate in a hidden folder.
- Open Outlook > Press Ctrl + 6 on your keyboard (or click the Folder icon in the navigation pane) to switch to the Folder List view.
- Scroll to the bottom of the list and look for a folder named Sync Issues.
- Check if there are recent logs (messages) inside this folder with red text or error codes.
- If you see a specific error code (ex: 8004010F), to better understand your situation, please share it.
I hope this information proves helpful and I look forward to your response!
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