Hi, Joosujin
Good day!
Thank you for posting to Microsoft Community. We are happy to assist you.
According to your description, the issue of your concern that your text disappears or distorted during the typing on your Office 365 Outlook desktop client.
First of all, please be kindly to understand to give an attempt for following steps:
- Right-click the Start button
(lower-left corner), and select Apps and Features on the pop-up menu. 
- Select the Microsoft Office product you want to repair and select Modify.
**Note:**This will repair the entire Office suite even if it's just one application you want to repair such as Word or Excel. If you have a standalone app installed, then search for that application by name.
- Depending if your copy of Office is Click-to-run or MSI-based install, you'll see the following options to proceed with the repair. Follow the steps for your installation type.
Click-to-run
In the window How would you like to repair your Office Programs, select Online Repair > Repair to make sure everything gets fixed. (The faster Quick Repair option is also available, but it only detects and then replaces corrupted files.)
MSI-based
In Change your installation, select Repair and then click Continue.
4. Follow the instructions on the screen to complete the repair.
In addition, please give it a shot by creating a new profile as below:
- In Outlook, select File> Account Settings > Manage Profiles
- Choose Show Profiles > Add.
- In the Profile Name box, type a name for the profile, and then choose OK.
If the issue persists, please be kindly to share your detailed client issue and then we can do more searching and test.
Sincerely,
Alex | Microsoft Community Moderator.