Are the other tools on your content editor toolbar (in visual mode) working.
The way you use the Hyperlink button, is you type the text you want in the editor, then you select the text, then you click the link button to create the link.
If you switch the editor to text mode, then you can type in the link HTML yourself like below
<a href=”linkUrl”>Your text</a>
But this has nothing to do with the theme, if really the above 2 methods do not work, you should try deactivating all non Weaver plugin and see if the editor work normally after that. If it does, reactivate one by one to find the culprit.