What is URL of your website?
1. Try to enable "Enhancing Management" and disable enhancing for Fabrik component (in Advanced section of template's settings).
2. If above doesn't help, check what css file is responsible for Fabrik component buttons and why it is not applied to mobile version. Note that it is possible to enable debug mode in template's settings and disable server-side optimization in MobileJoomla's settings to found what original css files are loaded on the page.