When I try to start a comment with @ and then someone's name, the whole string -- the symbol plus the name -- is being deleted. Is that a bug, or am I doing something wrong?
When you comment, the owner of the post (question or answer) on which you are commenting is automatically notified. Therefore, mentioning their name is redundant. It doesn’t do any harm, but it isn’t necessary either.
Someone thought it would be a good idea to automatically remove such redundant names. I don’t know who thought this or why: it’s one of many incomprehensible decisions taken by the SO overlords, and is certainly more confusing than helpful. However, that’s the way it is.
I think they’re removed only when they occur at the very beginning of a comment. If you work them into a sentence, as I often do, they remain in place.
They also remain in place when the person has made comments themselves.