@Pam-and-John0 Some guests don't have their notifications set, so they don't realize they have an airbnb message waiting. What I've done before when I don't get a response in a reasonable amount of time is to text the guest's phone#, telling them to please check their Airbnb messages and respond to me, or, if they are from another country that my phone plan doesn't cover, contact Airbnb, who can usually make contact with the guest.
That said, that's one of the reasons I don't use IB- the type of guests who think they can just book a place and show up at the door on check-in day.
For sure, 3*s or less for communication, and mention it in the review. The fact that other hosts have already mentioned it, and she still doesn't bother to communicate, seems to indicate that she just doesn't think it's important, rather than her not receiving the messages. And if she really isn't receiving the messages and saw that it was a problem for past hosts, you'd think she'd be more diligent about checking messages or making sure her notifications options are working.