TL;DR: Why don't offline maps download automatically via WiFi for me?
Long version: I have a Xiomi Redmi 4, with no data plan. I use wifi to download an offline map in Google Maps. I only have one map, and I use it extensively (daily). I also connect to a wifi network for a few minutes each day -- long enough to download all the other apps updates, etc.
According to this Google documentation, the offline map should update automatically:
Offline maps that you downloaded on your phone or tablet need to be updated at least every 30 days. When your offline maps expire in 15 days or less, Google Maps will try to update the area automatically when you're connected to Wi-Fi.
I've been using the same map for at least six months, and it never once updated automatically. Am I doing something wrong?
I read through some of this Google support thread, and it seems like it works for other people.