[A} In order to create challan/invoice after bulk stock transfer go to Inventory >> Stock Movement >> Approved as shown below
[B] Now open the desired bulk stock transfer inventory approval and click on "Action" button. You will get option to create challan/invoice.
[C] Create the challan/invoice through above options and created challan/invoice can be seen in Inventory >> Stock Movement >> Invoices/Challan.
Keywords - challan for internal stock transfer, invoice for internal stock transfer