What happens if you use beta7?
I tried to reproduce your problem with beta7 like this and it appears to work:
ComputationGraph computationGraph1 = KerasModelImport.importKerasModelAndWeights("X:/model.h5");
INDArray outputTensor1 = computationGraph1.outputSingle(Nd4j.rand(1,512,1024,2));
And it works, even though you will get a warning telling you: MKL-DNN execution failed - falling back on built-in implementation java.lang.RuntimeException: could not create a descriptor for a dilated convolution forward propagation primitive