Here you go.
There's actually two commands, CLEAR ZBUFFER and ENABLE ZBUFFER.
CLEAR ZBUFFER just clears the zbuffer. There were some weird cases were the zbuffer wasn't clearing with AdvancedSPRITES so I would have to use it.
ENABLE ZBUFFER is the command you want to call before you render any AdvancedSPRITES.
Some example code to test it:
SYNC ON
DXS INITIALIZE
test1 = DXS CREATE EMPTY SPRITE(200,200,255,0,0)
test2 = DXS CREATE EMPTY SPRITE(200,200,0,255,0)
pack = DXS CREATE SPRITE PACK()
DXS ADD SPRITE TO PACK test1,pack : DXS ADD SPRITE TO PACK test2,pack
DXS SET SPRITE CENTER test1,100,100
IK CREATE IMAGE 1,400,400,RGB(0,0,255)
DO
CLS
IF KEYSTATE(17) THEN BOX 0,0,200,200,RGB(0,0,255)
IF KEYSTATE(18) THEN PASTE IMAGE 1,0,0
IF KEYSTATE(19) THEN IK PASTE IMAGE 1,0,0,400,400
ENABLE ZBUFFER
DXS BEGIN SPRITE PACK RENDER pack
DXS DRAW SPRITE test1,MOUSEX(),MOUSEY(),0.9
DXS DRAW SPRITE test2,200,200,0.4
DXS END SPRITE PACK RENDER pack
SYNC
LOOP
MAKE MEMBLOCK FROM IMAGE 1,1