OK, this is weird.
I spent a lot of time trying to figure out why my image objects wasn't firing when I tapped on it (it works on desktop).
After several tests I noticed that it happened that on mobile screen the clickable area was off of the image (displaced). I found that someone had a similar issue and figured that it had something to do with devicepixelratio when using Phaser.CANVAS. I couldn't test with Phaser.AUTO because my mobile throws a WebGL error when I try to use it.
Any idea how to fix this issue? Thanks!