I haven't had this problem before, but I haven't used SMATH in a few months. I am currently running version 0.99 (build: 7822).
I am able to set up a header with an image, and several text boxes, some text boxes are smart like "current date" and "page X/Total".
However, once I save the file, close out of SMATH, and reopen the file, the header is GONE. Does anyone have an idea why the header disappears?