Almost all aspect of mail merge is working except:
Which thread should I respond to?
On the merge panel, when you go to merge to a new document, there is a tab for multiple merge records per page.
Oh, and if you dare to preview, the ID template can become corrupted. If you preview, uncheck the preview box, hit undo. But if the layout goes wonky it is because of previewing. It's a really long-standing bug. If that happens, copy the text frame with the merge fields to a new document and resist previewing.