The 20% is the Max Power setting for the second laser tube. I agree that 1.5mm thick should be pretty easy - Are you using air assist? Is it focused correctly?
For the jump, check the file to make sure you don’t have anything strange in it, like empty shapes. If you ‘Select all’ (Ctrl + A) does the selection border extend well beyond what you can see?
If it’s a new machine, don’t trust the focus blank - do a ramp test and be sure. It’s also not inconceivable that the lens has a different focus point than the manufacturer intended (some are labeled wrong), or that the lens was installed upside down (curved side should be up).