The Black Lives Matter organization just loves to target people with cries of racism. It's pretty much a given that a radical race-baiting outfit would launch such accusations against virtually every Republican, but it's been somewhat surprising that they've done the same to prominent Democrats. Earlier in his campaign, Bernie Sanders faced their wrath and, more recently, Hillary has too.
Fearful of alienating the black voters they take for granted, both Dem candidates have done a tightrope-walking dance to try and distance themselves from the movement while still quietly embracing it. It hasn't really worked, particularly for Hillary.