As I clearly explained in my post these are not beaten-up, dirty, scrawled-on notes. They are crisp, recent series, almost pristine notes with tiny pen marks on them. I have experienced problems exchanging them at several places, including my own bank
"They just want clean, unmarked notes" is what I wrote and that has been confirmed by your own experience.
You confirmed that the notes you have been unable to exchange have been written on (pen marks).