使用TensorFlow 2.0Alpha时，无法在Tensorboard中查看keras模型图

import tensorflow as tf
from tensorflow.keras.models import Sequential
from tensorflow.keras.layers import Dense

model = Sequential()
model.add(Dense(64, activation='relu', input_dim=100))
model.add(Dense(64, activation='relu'))
model.add(Dense(10, activation='softmax'))

model.compile(optimizer='adam',
              loss='categorical_crossentropy',
              metrics=['accuracy'])

# 训练模型
model.fit(x_train, y_train, epochs=10, batch_size=32)

tensorboard_callback = tf.keras.callbacks.TensorBoard(log_dir="./logs")

model.fit(x_train, y_train, epochs=10, batch_size=32, callbacks=[tensorboard_callback])

tensorboard --logdir=./logs