@staffname tag not working

@staffname tag not working

I have a new person in our Connect network, she's accepted the invite to the network, I'm following her, I've invited her to several groups which show she's a part of.
She has even sent a private post to me from Zoho.
BUT - whenever I try to tag her in a post, her name doesn't populate. I've never had this problem before and I can't quite figure out how to fix it...