Custom field hidden when document ammended

I have added a custom field to my puchase invoices. A user submitted an invoice with a 0 value in that field, now they want to update the field value. When we try to cancel and amend the invoice my custom field comes up with css hiding it.

I don’t see any setting to change this behavior.

As a work around if I save the amended document without making any changes then refresh my custom field shows back up. But I’d like it to be available to users as soon as they ammend the document. Doesn’t make any sense to save it without making any changes.

Anyone know what setting I might be missing?