OS X 10.11.1
MacBookAir6,2 with Intel HD Graphics 5000
I have this Automator app:
I use this to pad transparent PNG icons to the same size before using them on a website. Note how the Background Color is unselected; I never, ever select or change that. But now, when I run some icons through that, Pixelmator is *intermittently* adding black backgrounds to the final files. It is a crapshoot; they don't all always have black backgrounds, but at least one of them does every time.
The batch I'm currently working on is athttp://75thtrombone.com/links/pixelmator/icons.zip , and I'm trying to pad them to 34 × 31 pixels. The icons in that ZIP file have already been run through ImageOptim, since I forgot I needed to pad them first.
This problem only appeared today, which is the first time I've used the app on El Capitan.