When I got to the Amazon Appstore to download the update, I can download and install as normal. But when I open Minecraft, It is in version 1.13.1. Returning to the Amazon Appstore confirms this, as an "Update" button is shown as before I first attempted to download the update.
MCPE-59223
Cannot Download version 1.4
Resolved
Cannot Reproduce
0
Sounds like an Android/Google issue more so than a Mojang issue.