Just to make sure, have you seen these recent posts?
One other debugging tip - did you know you can view db-merge or data-to-spacy recipes (or any other built-in recipes)? This way you can see exactly what they're doing and debug/modify them.
Just run prodigy stats, then look in the folder with your Location:, and find the recipes folder. For db-merge, it'll be in the commands.py script and data-to-spacy is in the train.py.