raster-colorizer-* styles not working

[four43]

Hey all,

I first noticed an issue with raster-colorizer-* methods not working in Mapbox Studio Classic. After some poking around I found that they used to work, on an older version of Mapbox Studio Classic (v0.2.7) but not on the v0.3.3 latest. I ended up firing up a more simple pipeline just using node-mapnik (v3.4.9) to render a tile and am getting blank images, not even unstyled original tiles. I'm thinking this issue is due to mapnik somewhere. But after I hit node-mapnik it's pretty much a black box.

Please see the full writeup here: https://github.com/mapbox/mapbox-studio-classic/issues/1540

Thanks for the help, -Seth