Without additional details, it appears that this issue should be brought to your mail admin for troubleshooting and resolution.
Have you confirmed that the mail server itself receives mail for all other users, from the PANW mail servers, but this specific user, their email is not even received by your internal/cloud server? Have you confirmed there are no rules or mail routing flows on the server?
In order to best resolve this, the Live Community would suggest that you reach out to your partner/local SE and see what steps they may be able help with.
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