In the past 7 months my DM has asked after my DC once. That was back in June and it was two very specific questions, so not a general open question that would lead to further conversation. She didn't acknowledge the answer, just changed the subject. This is generally how our contact is. I will sometimes send photos or tell her some info about DC, but she doesn't acknowledge it, just talks about something else or doesn't reply at all.
I have not spoken to her on the phone in all this time. Contact is purely through WhatsApp. I have my reasons for keeping her at arms length, but do you think these are the actions of someone who wants a relationship with her grandchildren? Or a very clear sign that they have checked out?