I've just been called by my IRCC agent who said that they still did not receive my oath confirmation e-mail, while I have sent it same day.
So I have re-sent it and this time I received confirmation of receipt, and the agent confirmed that she has it.
She said that sometimes some e-mails could have issues, so please verify that you've received a confirmation.
My status in tracker was still the same as before the oath and I thought that it will be changed once the certificate is issued, so I just sent request to "standard hotline" where they have replied in a standard way - sit back and relax.
The bad thing though is that the agent said that due to remote working restrictions - she does not know when it will be possible to get to the office to print and send certificates. As they can process it remotely by the printing is "in person"
So another 4 weeks, may be more