I have two alias accounts & one hotmail account (from hotmail days) that were functioning fine. Meaning all emails sent to these accounts were being found in the respective account folders. So, for example, emails sent to email@example.com were found in the folder titled firstname.lastname@example.org.
It has been a couple of weeks at least since this has stopped functioning. Meaning all emails sent to the alias accounts are found in my primary email account folder. I had set up rules, quite a few, on my alias accounts all of which have been rendered useless.