Hi @Carmen Marroquin,
Does this issue happen in all notebooks or just a certain one?
Do you have your notebooks stored on OneDrive? If this is the case, we may try to close the notebooks and then reopen them to see the result.
Please make sure to uncheck Show only unchecked items option.
If above doesn't help, we may also try to clear the local cache for the notebooks and then see the result. To clear the cache, exit OneNote, fine the cache folder from the following location:
%userprofile%\AppData\Local\Microsoft\Office\16.0
and delete the folder named OfficeFileCache.
Besides, you may try copying the content with this issue to a new section to have a check.
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.