File Manager saving 0 bytes files ( No content)

I have an account which was migrated from cpanel.

When i try to save any file from file manager, all the content in the file gets erased (It becomes 0 byte file)

Ok

Looks like I have figured out the issue.

I have set disc quota and the quota of this account was exceeding the limit.

Instead of giving any warning, the system is deleting the content.

I think its a serious issue.

How can we overcome this?