We have had two instances (including myself) where customers with a Google email account, cannot receive codes from Microsoft.

These codes were required to add a Gmail account as a secondary method to access a Microsoft account.

The code was never received and it was not in the Spam folder in Gmail.
The only way to resolve it was to use another Gmail account.

Microsoft does not state that there is a maximum number of times that a Google account can be used as a secondary access method.
However, both Google accounts were already used as usernames for two other Microsoft accounts.