This has happened to me several times with Fluent and it is infuriating. I want to change the fluid_body Material to one of the materials listed but it is not in the dropdown menu. Why and how the hell can I change it? Such a simple thing. In Materials there is CLEARLY a mixture ready to use, so why is it not in the list of options? When I try to do anything it says "mixture-template is not define"... No KIDDING!!