I'm not sure why but when I try to set medium size (by passing "medium" alongside the other params in className) for icons, I get "unknown symbol" sign. I use semantic with react. It happens to whatever icon.
I use:
react: 16.6.3, semantic-ui-css: 2.4.1, semantic-ui-react: 0.83.0
From what I understand in your question, I think you wrote it like this:
<Icon name='users' className='medium' /> which is wrong.
The correct way is:
<Icon name='users' size='large'/>
Also, there's no 'medium'. The values are:
'mini', 'tiny', 'small', 'large', 'big', 'huge', and 'massive'
You can see its props here: https://react.semantic-ui.com/elements/icon/
