Reminders App will not Share a List

If you are having trouble sharing reminders then...

1. Check your internet connection: Make sure both you and your partner have a stable internet connection. If your connection is weak, it may prevent the sharing process from completing successfully.
2. Ensure you are NOT signed in with the same Apple ID: Check that you and your partner are signed in with the same Apple ID on your devices. If you are not signed in with the same Apple ID, you won't be able to share reminders.
3. Verify your settings: Make sure that you have enabled reminder sharing in your settings. Go to Settings > [Your Name] > iCloud and make sure that Reminders is turned on.
4. Also, Check where your Reminders are. Only iCloud Reminders can be shared.The pic below may give you a lead to look for your reminder. There are two sets of pics

This is confusing: "Ensure you are NOT signed in with the same Apple ID: Check that you and your partner are signed in with the same Apple ID on your devices. If you are not signed in with the same Apple ID, you won't be able to share reminders."

We have separate Apple IDs -- we always have. We do not share an Apple ID. We do share an iCloud storage plan -- and most of our shared reminders work, but three do not. As "owner," I have "invited" my partner to share these lists, but it still shows "invited," suggesting that he has not accepted the invite. But he doesn't know how or where to accept these invites.

Any suggestions?

Thanks.