We have just finished refactoring our AgileData Collectors from using Singer to using Meltano.
I was updating our user guides and noticed that Shopify just changed from Custom to Private apps, which meant setting it up was a little different from last time we did it.
Thought I would post a link to our doc on how to enable it on the Shopify side in case its helpful for folks.
http://docs.agiledata.io/features/collect/saascollectors/shopify.html
(Ignore the blank screens/images, they will be screenshots of the AgileData App when we have finished the dev for the Data Collection pages)