Hi PY,
Sorry for the inconvenience the problem caused for you.
Based on your description, when you type and copy-paste on OneNote for Mac, a "Please wait" window will pop up and freeze the screen. I tested on OneNote for Mac version
16.42 on my side, and there was no problem.
Here are some of my suggestions, you can try them first and tell us the result.
If this sync issue is happened in all notebook:
1.You can remove OneNote cash.
a. Sign out and close all office apps.
b. Go to Finder, find
~/Library/Containers/ (press command + shift + G and enter this path)
c. Find “com.microsoft.onenote.mac” folder, select and move it to trash
d. Restart Mac and sign in
*Note: please remember to backup your contents before doing this step.
If this sync issue is just happened in a specific notebook, you can close this notebook and your OneNote and reopen it to see the result.
If the problem persists, could you please provide me some information?
1. OneNote version number(open OneNote>on the upper left corner, click OneNote>About OneNote).
2. Did you make any change before the problem happen, such as: MacOS update?
3. Does the issue happen to a specific notebook or all notebooks?
Best regards,
Jazlyn