Here is an old post with the same issue.
I am using a drop off library and it works great OOTB. However, I would like to use a custom edit form. I can create the form and use it no problem, but when saving it, it only saves the document and doesn't submit it.
When I compare the two forms, I immediately see that the default one has a button that says "Submit", whereas the custom one has a button that says "Save".
Can I edit my custom form so it will submit rather than just save?
Is there a way I can change this <SharePoint:SaveButton runat="server" ControlMode="Edit" id="savebutton2"/>
to a submit? I did some basic searching but couldn't find anything on SharePoint:SubmitButton
.