We did get our AOR in letter mail back when we applied (few years ago) and we moved since we submitted the interest to apply (so 2 addresses for the sponsor). They request formal address change proof to show that we changed our address from the previous to the current one. And we did send the proof.timeline:
submitted: nov 6 2021
ghost email - feb 23 2022
aor: mar 26 2022
application linked - mar 26 2022
medical passed - April 5 2022 (they considered the medicals given in 2019 for super visa)
received Sponsorship approval in mailbox on April 6, letter is dated as April 4th.
Now - they are asking for the pending documents(which include PCC). The most recent appointment I could get for a PCC from India is for May 2 2022 and I imagine it will take at least another 20 days to get it back
Question - Is there a deadline to submit PCC after receiving the Sponsorship approval letter?
Weird that they sent the Sponsorship approval letter in physical mail rather than an email. is it common?
In your case, double check to see if they have your email address on record from the linked application.