Blank Fields on saving after Config Error is rectified

Ok, so this is really strange and never happened before to us. Before I get into it. Have tried deactivating, uninstalling all plugins, reinstalling wp, theme etc.

Basically, we make a new form, change the Additional Headers input so that there is an error. ie. [email1] instead of [email]. Then when you save the form, bang!! All fields including the ‘Form’ content is removed.

If the form is created and there are no errors, the form will save no problem. As soon as there is an error in the ‘Mail’ tab field(s), it’s trashed.

Being a backend issue, not quite sure how we can get assistance unless someone has experienced this before.

Any help would be appreciated.