Garbled PDF output for a chapter that passes Paratext's marker checks

Question

When I try to run ptxprint on a specific chapter in my project (Luke 2), a strange and garbled PDF comes out. The first page is mostly blank, but has a few isolated words scattered about on the page. (Searching for those words in the chapter did not suggest anything obviously wrong to me.) More to the point, the whole book passes the Paratext marker check. So there's a mismatch someplace.

If someone would send me an email (from an identifiably official address) I will be happy to share the SFM file.