@vinhdoan.thoi You could try:
- lowering print speed on layer 1.
- running the dynamic flow rate calibration for that filament to ensure you aren’t under-extruding (which would undermine adhesion).
- drying the filament. If moisture is too high, it doesn’t stick as well.
- if all else fails, try a super strong build plate adhesive like vision miner as a stop-gap until you figure it out. However, that runs the downside risk of it sticking too well, so you might try lesser bed adhesives and work your way up to that as the hail mary if none of the lesser ones, like magigoo, get the job done. There’s a whole host of them on the market. You shouldn’t need it at all, but, if you just need to move on with it, you gotta do what you gotta do.
4. You could abrade the surface to increase adhesion. Shouldn’t be needed, and obviously a last resort.