A small group of scientists started to speak up in various forums arguing that the original scientific experiments (1960s?) which calculated things like droplet sizes, distances traveled, times to evaporation, etc--the numbers used to determine how far particular kinds of virii can travel and how long they can persist in the environment--was irredeemably wrong. These bad metrics were and still are used to build transmissibility models.
According to more modern metrics and models, while not airborne as its strictly defined, Ebola virus can transmit much more readily and further than what is currently taught. TL;DR: aerosolized droplets can carry the Ebola virus much further and longer than believed. Bifurcating virus types into "airborne" and "not airborne" is dangerously simplistic as infected aerosols can have risk profiles closer to that of traditional airborne virus types, particularly for a virus like Ebola.
I can't find the original article I read--an article by the researcher who, IIRC, was the first or one of the first to empirically show the critical flaws in the original experimental results that current models rely upon. But this paper seems to have a good discussion of the issues: "Transmission of Ebola Viruses: What We Know and What We Do Not Know", https://mbio.asm.org/content/6/2/e00137-15
EDIT: The original article I read: http://www.cidrap.umn.edu/news-perspective/2014/09/commentar...
Though maybe the differences are by-products of the poor models mentioned in another comment.