This is out of our scope as it is not theme related.
But my starting point would be:
1. Flush the device browser caches – to check for browser cache problem.
2. Clear and disable any plugin caches and repeat 1 to see if uncombined files work.
3. Test a different browser on the device to see if it is device or browser related.
4. Try Chrome developer tools – not sure if will work with the native browser, have no experience of Xiamoi: