The national Black Lives Matter movement claims $33.4 million of its cash is being withheld by one of its progressive partner organizations, The Post has learned. In a scathing lawsuit, Black Lives Matter Global Network Foundation accuse the Tides foundation — backed by George Soros — of alleged "deceptive business practices" as well as "egregious mismanagement" of its money, while demanding its return. The lawsuit was filed last year, but the stakes were raised on Monday when the BLMGNF — which oversees its other regional operations — asked the California Attorney General to step in and investigate Tides.