The yearbook pics were circulating online some time before the draft - this alone makes me think it is highly unlikely the Bucks FO did not know of the rumours.
Add to this that Maker is originally from Sudan, and scandals evolving the age of sub-Saharan African players happen all the time (esp. in soccer; we had discussed this in another thread).
tbh, I'm not convinced yet either way; there are legit concerns about his age, but it does not seem to me to be definitively proven. But it sure is an interesting story to follow.