How to fix an error when appointing an administrator in a telegram group?

Question

Telegram

The essence of the problem:
I can not appoint a person as an administrator in a group.
He is in my contacts, he has the necessary permissions in the settings.
We tried to create another group, everything is fine, it can be assigned as an administrator.
The problem is only in a certain group.
The error itself when trying to assign "You cannot invite the user to groups because of his privacy settings"

Now he was kicked out and I can not even invite him back and he cannot follow the invitation link (writes the term has expired).
I repeat, in any other groups everything is fine, the problem is only in one group.
The rest of the participants are invited and appointed by administrators without any problems.

Answer 1

up?