You may need to confirm that forwarding is active for your account.
1. Access your gmail settings page *for your shared mailbox*
Login to the gmail account where you access your shared mailbox (this may be something like firstname.lastname@example.org). Click on the gear icon in the upper right-hand corner of Gmail, click the ‘Settings’ option from the dropdown menu and click the ‘Forwarding and POP/IMAP’ tab from the top menu.
2. Confirm the forwarding
Go to the forwarding tab and make sure forwarding is enabled.
(Click on the Gear icon → Settings → ‘Forwarding and POP/IMAP’ → Tick ‘Forward a copy of incoming mail to’ and select the email address you just confirmed).
Don’t forget to save when you’re done.