Outlook - read receipts not moved to Deleted Items

[Suzanne]

Hi guys,

I sent read receipts with all e-mails and have set Outlook to delete
processed receipts automatically:

For external recipients, the delete-after-processing usually doesn’t work.
However, for internal recipients, this worked until today. Now when a receipt
is processed, the tracking on the sent item is updated, but the receipt is
not deleted from my inbox.

I double check that "After processing, move receipts to" has been selected
and set move to Deleted Items.

Any idea why?

Thanks,
Suzanne