Sorry to hear that - no consolation to you, but mine eventually dropped into the o2 app on Tuesday evening for Saturdays show.
I know I'm an old fart but I'd much prefer to have real-life, hard-copy, proper-printed tickets in my hand than a QR code / ticket on an app!! I'll still be nervous until I'm physically allowed inside the building!!
I had problems on my phone downloading til that day too and I agree why is a ticket so hard? I wonder if the empty seats wr saw around is because of stuff like tickets not delivered in time.