Cannot receive calls from one number that is NOT on my blocked list

it could be due to a few different settings or configurations on your iPhone or iPad. Here are some troubleshooting steps you can follow to resolve the issue:

Check Individual Contact Settings:

• Open the Messages app on your iPhone.
• Find a conversation with one of your family members.
• Tap the contact name at the top of the conversation to open the contact details.
• Check if "Hide Alerts" or "Emergency Bypass" is enabled for that contact. If so, toggle it off.

Check Mute Conversation:

• In the Messages app, swipe left on the conversation with your family member.
• If "Hide Alerts" or "Mute" is enabled, tap on it to unmute the conversation.
• Hide Alerts watch the GIF below

For Hide Alerts please see the pic 1 below. Follow Pic 2 for two scenarios; DND+Hide Alert and Only DND

Pic (Hide Alerts)