After hours of calibrating the Mitre saw and almost losing my mind over it, it is done.
No wonder I struggled with this saw. The calibration was maxed out and I had to file the elongated holes in the fence longer to actually get it true. Plus, aligning the blade to the slot first was a real hassle. Eventually made a spacer with good result.
Then it checked out at 90° but not at 45° until I realized this red square had a problem too. You can probably spot it!