I have no idea why it does not work for you. If you want, can you share the image you are trying to show in the push notification? I just want to confirm it is not the image itself causing issues.

Did you simply edit the message and added an image, saved the message and updated the journey? If that does not work you might instead want to create a new version of your journey, then edit the message, add the image and publish the new version of the journey. Also, what is the URL of the image you...

The app does support images in push notifications already. Just add an image to the message, for example: https://ridmaur.github.io/tutorial/luma/images/luma-logo01.png.See sample screenshot.