I'm inclined to say it was a case of too much demand, too little supply.
People don't seem to be having issues receiving the smaller items like Amabri or DanMachi but the heavier stuff like Parasyte and Akame seem to be getting"lost"
Arguably they just processed everything and waited for non-receipt messages to appear to refund those who followed up on their orders.
I messaged them yesterday about my Akame ga Kill sets and got the generic "in transit, send replacement" response, emailed them again this morning got the "lost, refund" for Part 2, emailed about Part 1 which was in the same order and got the "in transit" response again.
Seems to be a case of ask once and get told it's coming, ask twice and get a refund.
Be funny if they refund everyone and the stuff shows up.