OKLAHOMA CITY — The Magic took one step forward but two steps back when it came to player availability Saturday night against the Thunder. Forward Jonathan Isaac, who missed nine games due to a right hamstring strain and a 10th Friday night in Miami because of an illness, was available again for Orlando at Paycom Center. Although the versatile defender made his return, the Magic were without guard Markelle Fultz (left knee injury maintenance), center Wendell Carter Jr. (right knee tendinitis), forward Franz Wagner (right ankle sprain), guard Gary Harris (right calf strain) and forward Joe Ingl…