The project assets inspector and the render queue annoyingly use different code to check for missing files. The asset inspector checks for which files are genuinely needed to render the project, whilst the render queue just does a dumb check for the mention of a material. So, if you have a node in a material that isnt linked to anything, the project asset inspector will say "yeah, not connected to anything, dont worry about it" whilst the render queue shits its pants, throws up a red light and tells you the world is about to end. Options:
- hunt down the unused nodes and delete them
- change the c4d prefs to ignore render queue errors and just render anyway
- search your hdd and just copy the offending files into /tex so the render queue shuts up