Save the person’s phone number in your contacts
Ask the group admin to add your contact name to the group description or mention you in the group chat
Send a message in the group so your name appears in the chat
Make sure your WhatsApp profile name is set correctly
Check that the group member list is not being viewed from an unsaved number
If you want your name to show for others, they must save your number in their contacts
Update WhatsApp to the latest version
Rejoin the group if your name is not displaying properly