Tensorboard on Google colab doesn't work, calls localhost:6006

I am trying to use tensorboard on google colaboratory.
Following this guide: https://www.tensorflow.org/tensorboard/tensorboard_in_notebooks
I have ran %load_ext tensorboard, then %tensorboard --logdir='ssd_mobilenet'
ssd_mobilenet is my working directory where events.out.tfevents files get created.
I then run the object_detection learning via model_main.py.

When I open page inspect (Google Chrome) click on scallars in tensorboard, I can see a bunch of failed calls to localhost:6006

Just to confirm events are being actually created, %tensorboard --inspect --logdir=ssd_mobilenet returns summary of event file.