Has anyone else been ghosted by a buyer after receiving an offer?

Currently selling and this whole process is mad.

Buyer viewed our house, put in an offer £20k below asking. We countered. That was 10 days ago and we’ve heard absolutely nothing since.

If they don’t want to proceed that’s fine - but surely a quick courtesy email to the estate agent isn’t too much to ask? These people are ready to drop quarter of a mill on a house only to then completely disappear?

We’re just left hanging not knowing whether to wait or move on. Is this normal? Do buyers just vanish after making offers? Has anyone else experienced this?