Maps ETA does not send notifications to any of my contacts

When I share ETA with a contact, the Maps app shows that it is sharing, but the recipient never gets a notification. I tried multiple recipients and none get notifications. If those recipients share ETA amongst themselves, they correctly get a notification. If they share ETA with me, I correctly get a notification. Why is it that I am able to use the share ETA feature but no one gets a notification about it? I enabled cellular data use for Maps, have no one in my blocked list, and the “Share ETA” slider in settings is on.