Hi Sam,
The Google OCR button and the tool https://tools.wmflabs.org/ws-google-ocr/ is giving 500 internal server error output from today, although the Cloud Vision API is working fine https://cloud.google.com/vision/docs/drag-and-drop.
We have reported in phabricator here https://phabricator.wikimedia.org/T190216. It would be great for us if you please look into this matter urgently as all our options are suddenly ceasing to work.