I have an alternate theory: it’s the sheer volume of char that makes cork difficult. The char absorbs a lot of the energy and prevents the laser from reaching new unlasered cork in subsequent passes.
Whatever the cause, that’s pretty thick stuff and cork is not always very easy to get through.
My suggestion is to possibly do two things:
First, use full power, not 100. They aren’t the same, especially if you have a GF pro.
Second, if that doesn’t work, do two passes but do them one at a time so you can set a different focal height. I’d go the first pass at 0,36” and then the second at about half that, 0.18”.
I’d set the power at full and vary the speed in a proper material test as described in #6:
Good luck, as has been mentioned above cork can be difficult and inconsistent.