The "Suggest" button for a chapter title only seemed to read the beginning of my chapter. Has that changed?

Yes. "Suggest", next to the chapter's title at the top of the chapter editor, used to read only the opening of the chapter. From version 1.9.24 it reads the chapter from beginning to end: the whole chapter when it is short, and its opening, middle and ending when it is long. The title ideas therefore fit where the chapter goes, not only how it starts. Click an idea to use it, or edit the title yourself by clicking it.