'preview' icon works only once

1. Create a new File document type, attach an MS Word docx file to it.
2. navigate to this document and wait sufficient time for the PDF preview to be created
3. click "More" in the context icons top-right and select "Preview"
4. close the preview pop-out window
5. try to repeat step 3 – the preview icon is simply missing.
Multiple browsers tested.

Notes:

• reproduced on 8.10-HF02
• refreshing the page makes the Preview link come back