Sorry again, you are right the <br/> tag that don’t really make sense here.
Just tested this in my development website with ACF PRO 6.7.0.2 and the stored value is actually not containing <br/> tags:
<ul>\r\n \t<li>1</li>\r\n \t<li>2</li>\r\n</ul>
what version are you running? any special config or plugin that might alter the wysiwyg editor ?
