Post schematic, PCB design images, and oscilloscope.
It sounds like the same problem I had here, which I never resolved. But in my case it’s DRV8300 and none of the high side fets will turn on. I gave up and redesigned for the very similar FD6288 which worked for me before here, and am currently waiting for the new boards to arrive (probably monday). But if you’re having the same problem with it, perhaps we can find a clue by comparing our designs and get DRV8300 working too.