No icons appear from the HTML export

Steps to reproduce:

1. Create a page e.g. P1 and add some content
2. Create a child page P2 (P1/P2)
3. Create a child page P3 (P1/P2/P3)
4. Export as HTML page P1 with children
5. Extract the zip
6. Open the Index page
7. Open each page and observe the UI

Expected results: The UI of the exported pages is the same as the original ones.

Actual results: Icons don't appear. Results can be seen for IE/Firefox and Chrome browser.

NOTE: HTML export works on 9.4.