The new SF Symbols palette color feature was working perfectly for me in beta 4, but as soon as I installed beta 5 all my symbols started rendering in a single color. After some debugging, I realized that this is only happening when the image is created via drawRect.
Hopefully this is just a minor bug that will be fixed in the next beta, as I just spent an entire week moving everything over to custom symbols (and I have to render them via drawRect)...