Simply be being present in a patch and being enabled, a barebones jit.gl.pix object seems to stop a jit.gl.light @type spot from functioning.
This is just the tip of the iceberg as far as problems I've been having with jit.gl.pix, materials, lighting, blending - but it's been difficult to isolate each specific problem, because often when I try to recreate the problem as an example outside of the context of an actual project, it simply goes away.
Anyway, this one didn't go away. I would appreciate it if anyone else could corroborate. Or show me where I've gone wrong. Or suggest a workaround.