I know it's a bevel cut. The fascia boards are joined at the corners. I tried a 45 degree bevel
Angle but the boards cuts would not line up. What is the adjustment # on the miter saw?25768
My Miter saw only banks to the left for fascia boards, trim, maybe that is the problem?

Get yourself a protractor or a bevel and measure the angle your are cutting, your saw could be off. Measure the corner itself and divide that angle in half, most homes do not have exactly 90 degree corners on walls.