Dear Jufer Zhao,
Welcome to the Microsoft Community.
I understand that you are unable to edit a folder in OneDrive after sharing it to another account for a few months, I understand your frustration and will do my best to help you troubleshoot.
In order to better identify the cause of the issue, I'd like to know a little more about it with you:
- How are you viewing the edit permissions? Is it in the web version of OneDrive(select Sharing - ‘Click on the three dots of the file - “Manage Permissions”)?
- Is this only happening in one file or is it happening with your other files as well? I noticed that you described not being able to view it properly on other accounts as well, if this is only happening on one file, it's most likely a file-specific issue, make sure that the current file is fine in your OneDrive and that the permissions manager also has the address of your other account (which can be seen in the web version of Manage Permissions).
- Also, I noticed that you are viewing the accessed files in OneDrive on your iPhone, what is your current version of OneDrive? Have you tried updating the current version of OneDrive? Suggest you could try to troubleshoot if the issue is with the current OneDrive.
- Are there any error messages that appear when you are unable to edit, or when you access a shared file? If so, you can share with us a screenshot, I think it will give us a clearer picture of the issue.
Sincerely hope you can understand, as the initial information may not give us a clear idea of the direction of the issue. I hope you can share more information with us to troubleshoot and test.
Thank you for your understanding and patience.
Best regards
Isabella-MSFT | Microsoft Community Support Specialist