First, I know there is another posting that appears to solve this.
It is old, and does not work for me.

I start Chromium-browser and it asks if I want to import bookmarks.
When I click yes, it tells me there is "no supported browser found".

If I go to Settings -> Users -> Import bookmarks and settings
and select the HTML file created when I exported bookmarks in Firefox all I get are the first 2 folders.

I'm fed up with Firefox not displaying pages properly (character encoding problem). I have accumulated over 500 bookmarks in folders up to 4 levels deep, and switching to another browser will be painful if an automated process cannot be found.

If you open the bookmarks.html directly in browser as a webpage, does it have all your bookmarks? If not then FF badly exported them; a had similar issue, the reason was (i believe) i had my bookmarks in a bookmark toolbar, not menu.
Other than that, i'm not sure what might be the problem.

Opened as a web page I can see them all. Initially I will access them that way and gradually save them as they are used.