I used for my thesis the
\blacktriangledown commands and they work. I used the
book document class.
Instead now I need to replicate them on a presentation, using the
beamer document class. However in such a case the symbols do not appear and no related error seems to occur within the log.
EDIT: the symbol goes in conflict with the package
unicode-math. However, when removing this package my colored bullets in math mode stop working:
EDIT 2: solved by using
\bullet instead of
amssymb. I'm not sure that this package is always loaded in