ADE 4.5.11.187658 and TOC in Navigation-window

If I load an Epub in ADE, it should display the toc in the Navigation on the left. However, I recently got an epub for which ADE doesn't display this. Navigation stays blanc/empty. The epub does have a Table of Contents, which is displayed on its own pages. This is the only epub in my library with this issue.

So, where does ADE get the toc from that is displayed in the Navigation-window? With Sigil I can see that the epub does have a toc, as any other epub in my library. But for one reason or another it doesn't "see" it or it skips it.