Error when extracting frames (uniform with start

Error when extracting frames (uniform with start > 0)

Win10, DLC 2.0.4, GPU environment

After setting up the project and the config file, I run the following code to extract frames:

deeplabcut.extract_frames(path_config_file,'automatic','uniform',crop=True, checkcropping=True)

I get the following dialogue:

Config file read successfully.
Do you want to extract (perhaps additional) frames for video: D:\dlc-blinking\xxx\eyes_only-Guy-gpu-2019-01-29\videos\animal_3_video_2_150fps_correct.mp4 ?

yes/no

To which I respond with yes. However, I then get an error:

  File "C:\Users\xxx\AppData\Local\Continuum\anaconda3\envs\dlc-windowsGPU\lib\site-packages\deeplabcut\generate_training_dataset\frame_extraction.py", line 168, in extract_frames
    ax.imshow(image)

UnboundLocalError: local variable 'image' referenced before assignment

I can attach my config file if necessary to debug. I couldn't figure out the cause, but this worked just fine on the CPU env.