I recently checked the usage of fill-paragraph-function. Currently, a
number of modes ignore it and simply map Meta-q (or something similar)
to a different function, as for example:
(define-key map "\eq" 'LaTeX-fill-paragraph) ;*** Alias
(define-key km "\C-c\C-q" 'bibtex-fill-entry)
It seems to me that this is due to incompatibilities?