Typedef Function Pointer Invoking Issue
This answer contains a few debugging guidelines, as I don't know what the problem is and don't see how one could tell without a good deal more of information.

I suggest creating a Minimal, Complete, and Verifiable example (MCaVe) of your code, not just snippets, so that other people can compile and run the code, thus being able to observe what happens in more detail and perhaps with added debugging output.  

I'm presuming your callback is triggered as a consequence of an interrupt occurring.  I suggest you write the MCaVe to depend on a pin-change interrupt, rather than a motor-controller interrupt, to allow testing on a system consisting of no more than an Arduino with a button, a serial interface, and perhaps a few LED indicators.  Pressing the button would change pin voltage and cause an interrupt; your ISR would turn on an LED to signal it handled the interrupt, then trigger the callback.  The callback routine would turn on another LED as its signal.  The main loop would read the pin register bits for the two LEDs, record and report the times they came on, and turn them off after a second or two.  If you get a simple setup like this to work, the technique probably would carry over to your motor-controller case; or if not, probably being a smaller program and setup should be easier to debug and figure out why not.