You have to set the Mesh Element Order to Linear if you want to use 8 node hex elements and you have to set the Element Order to Quadratic if you want to use 20 node hex elements.  You have left it Program Controlled and it meshed with an element order that does not match the SOLID65 element type.  Furthermore, if the element type is only a Hex element, you can't allow the mesh to have any Tetrehedral shapes (and vice versa).

SOLID65 is an obsolete element. I can't even find it in the 2019 R3 help system.  Consider changing to a current technology element.