After a long time fiddling I've just realised what is causing the problem (typically 5mins after giving in & posting the question on here).... The illustration layer has a layer style>drop shadow applied to it. When this is deleted the track matte works.
Is there no way to apply a layer style to a layer which is being masked by a track matte?
Do you use OpenGL? Anything with continuous rasterization? Other Alpha-centric effects that may override things? Have you tried to pre-compose the AI file? Do you use multiprocessing? Indeed this sounds strange, but without seeing the AI file and the AE project this may not be possible to unriddle. If you use any acceleration features liek MP and OpenGL then turn them off. Also, when saving the AI file try to save back to an older AI version (CS3 or CS4). i seem to vaguely recall issues with CS5 files under certain conditions...
1 person found this helpful
Ah, i see. Yes, layer styles do change rendering order. If it's just a drop shadow, you can always use the equivalent effect. Since effects process in a different order from layer styles, that would work. Otehr than that, as I wrote, pre-compose your AI file.