Last day I fixed same issue in another store .
There issue was JS which prevent add to cart on mobile.
And to fix it I have to fix that manually check the code and now its working fine.
If you want you can contact me through email with details and we'll discuss it.
It's working on all Android devices that I tested. We'll need further information to be able to reproduce the bug and assist you.
1. Which version of Android was it?
2. Which Android browser was it?
3. What product page was it?
You mentioned that you're losing customers because of a bug, if that is the case, install a fresh copy of the same theme you're using and leave the other one offline until you can get it fixed.
Usually this happens when bad code is injected from an installed app.