Unable to join Microsoft Family Safety family group: "Unusual activity detected"

Hello,

I am experiencing an issue when trying to join a Microsoft Family Safety family group.

My Microsoft account is an adult account, and I can sign in to it without any problems. An adult family organizer has sent me an invitation to join their family group.

However, when I click "Join", I receive the following message:

"Unusual activity detected. We detected unusual activity. Please wait for the invitation to be sent again."

Here is what I have already confirmed:

• My Microsoft account works normally.
• I can sign in to Microsoft services without any issues.
• The family organizer has resent the invitation multiple times.
• The error only occurs when I attempt to join the family group.
• My account is an adult account, not a child account.

I would appreciate help with the following questions:

1. What does this message mean?
2. Could it be related to an account security restriction?
3. Are there any steps I can take to successfully join the family group?
4. Has anyone experienced a similar issue and found a solution?

Thank you in advance for your assistance.

Additional information: The organizer can send invitations successfully, but every time I try to accept the invitation, I receive the same "Unusual activity detected" message.

Screenshot of the error can be provided if needed.