Hi @jyingling
I would lodge a support ticket to your host and ask them if any errors have been logged within a time frame (when you saved the post) that could help explain why some data was not saved?
The issue could be that the database did not allow x amount of data to be modified in one page load, or that the server did not allow x amount of variables / memory to be used in one page load.
Hope that helps.
Thanks
E