When I give add bibliography a command window opens and says 'Replace this Zotero field' .When I close it or click yes it goes back to the previous window without adding references.
This implies you may be trying to add the bibliography within the field for the citaiton you just added.
Start a new document, add your reference, hit "end" or the right arrow key several times to make sure you're out of the field for the reference, hit "return" a few times & then insert the bibliography.
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Start a new document, add your reference, hit "end" or the right arrow key several times to make sure you're out of the field for the reference, hit "return" a few times & then insert the bibliography.