Hi @Sanwal Chaudhry ,
Check the version of the Outlook client(File > Office Account > About Outlook), and make sure that you upgrade it to the latest(File > Office Account > Update Options > Update Now)
- Try to clear RoamCache folder will force Outlook to rebuild it again with a fresh cache to resolve the error: Press WIndows+R, type %localappdata%\Microsoft\Outlook, and click ‘OK‘ or press Enter.
Open the RoamCache folder and delete everything. - Sometimes Outlook view settings may also lead to the error. You can reset Outlook’s view settings to resolve this error.
Press Windows + R, type Outlook.exe /cleanviews in the Run window, and click ‘OK‘ or press the ‘Enter’ key. - If above doesn't help, try creating a new Outlook profile by following these steps:
Open Control Panel > Mail > Show profiles > Add a new profile and connect your account to see if the issue continues.
If the issue persists, would you mind offering me more information for further analysis
- Whether you cannot view all encrypted message in your inbox folder, or just specific ones.
- If adding your account to another Outlook client, whether the issue will appear.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.