Office cannot import splitted document with numbering

Hi,

I tried to import some documents that have headings with a number. I checked all all headings level (1 to 6) to split.

Expected results:
The document is imported with a sublevel for each title.

Actual results:
The document is imported as if Office does not recognize headings (one big block of text).

I tried with the same document without numbering, with the same style set ("Word 2010"). This time, XWiki succeeds in importing and splitting according to the heading levels.

Importing doc and docx files produces the same results. Attached are small examples of doc and docx files, with and without numbering. In addition, checking or unchecking "filter style" does not change anything.

I should add that no error appears in Tomcat logs.