This has been a bugaboo for a while. Notes converted to grace notes that occur as a pickup to a downbeat seem to intransigently snap to the primary note’s measure, which looks/and is wrong. This is an extreme example with many notes, but sometimes it’s preferred for a rapid succession of notes, in that it describes which notes in the “gliss”. Even if it were one or two grace notes, it still seats them IN the same measure as the downbeat. I’ve not figured a work-around.