CNC engraving extruded acrylic / rpm settings

Hi there,
I’m trying to cnc engrave extruded 5mm clear acryl plate, but i’m not getting the settings right. I can’t find any solution on the forum. I’m using the 30degrees v-bit v-bit included in the extra 3-piece bitset.
I tried it with Luban and Fusion360. No matter what cutting depth (0.3 , 0.5 , 1mm) work speed (200, 300, 500,800 mm/min) I always seem to get a melt stuck at the tip of the V-bit. Is extruded possible to engrave somehow? Is there a way to set the spindle rpm in the luban software without diving into the gcode? The rpm settings in Fusion aren’t applied to the gcode after postprocessing either… Always 12000rpm.
I hope someone made this work before.