User Problem

When you react to a comment on a card, users that watch that card receive notifications about that action on browser and desktop, but don't receive the same notification on any of the mobile apps.

Current Workarounds

You can skip using mobile apps, instead open the browser of your choice on your phone and go to trello.com there and log in as you normally would. You can see all the notifications using Trello on your phone through a browser.