This used to work and it appears it does not anymore. Like, very recently.
When we push an image to a LINE User (POST https://api.line.me/v2/bot/message/push) and the originalContentUrl (https://developers.line.biz/en/reference/messaging-api/#image-message) is a URL that points to data on Azure/AWS/GCS only the preview is accessible on Android clients. The actual picture is not. We get an error message basically saying the client refuses to download the image since it does not come from LINE servers....
If the data is on Box.com, the preview is not even available on Android.
Note that on iPhone clients, all is well. we get the preview and the picture data.
How can we solve this?!?