On the entity invoice I have a small JavaScript that set the value of totaltax to null when clicked.
Xrm.Page.getAttribute("totaltax").setValue(null);
Everything is working as intended until the invoice is saved, then the totaltax field is recalculated with the values from the invoicedetails.
I have no JavaScript that runs OnSave. I have deactivated all the workflows / business rules on the invoice entity. And there are no plugins associated with the Invoice.
What is causing the totaltax field to be recalculated, when the invoice is saved?