My friend cannot see any chat messages from other players in the Realms world I created. However, we can see the messages they send. This issue has been ongoing for a while.
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Please try below. Please also see https://report.bugs.mojang.com/servicedesk/customer/portal/9/REALMS-10191
They need to look at the own settings in xbox settings → privacy and safety. Could be this setting: “Others can communicate with voice, text or invites”.
https://www.xbox.com/user/settings/privacy-and-safety