@Jacqueline11 This is not an answer to the original question and this "solution" is almost useless to most customers. Customers usually do not access invoices from the Sales tab and should not be forced to. Invoices are typically accessed from the Search feature or from links. When an invoice is OPEN, everything we need to see about that invoice should be available LIKE IT WAS BEFORE. 

We are not requesting a new feature. We are just requesting that this vital feature NOT BE REMOVED.

Please assure that the invoice Activity History will be reinstated on the OPEN invoice as soon as possible. In the meantime, our business will be looking into migrating to a different system in the coming new year.