So the issue fixed itself when I switched to the Google drive PDF viewer. But yeah, any sentence that starts with "th" is completely gone, and many instances where "fi" should be the text is missing.
sounds like a ligature issue in some PDF viewers, may need to make sure to embed the font if it's not already done. Those are two common ligatures where the font combines the two characters to make a special glyph like dash and greater than sign (->) could become an arrow.
