Health App Sharing Invitation Not Received

I'm experiencing an issue with the Health app's sharing feature on my iPhone. I can successfully share my health data with another user (Person B), and it works fine. However, when Person B tries to share their health data with me, the invitation does not arrive on my device, even though their Health app shows the invitation as "sent."

Here’s what we’ve already checked:

• Both devices are running the latest iOS version.
• iCloud Health sync is enabled for both users.
• Two-factor authentication is active for both Apple IDs.
• Both of us have each other’s iCloud email and phone number in our Contacts.
• iMessage is active with both phone numbers and iCloud emails enabled.
• Notifications for the Health app are turned on, and no Focus modes are blocking them.
• We’ve tried stopping the sharing, restarting both iPhones, and resending the invitation.
• There’s enough iCloud storage on both accounts.
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Despite these steps, I still don’t receive the invitation, and there are no notifications or pending invites in my Health app. Please assist in resolving this issue or provide guidance on next steps. I can provide diagnostics if needed.