The consistent criteria finally clicked: image files with spaces in the name. For example: Dark Knight.png
Works fine locally, but when it gets ingested for presentation on Twitch in hosted testing, something goes wonky and it gives the 505 error when it tries to pull it. I’ve corrected my file names and such to work around it, not sure if this is a known problem and documented somewhere that I missed, but if it isn’t would be great to get that somewhere visible. 