[NTG-context] Functionnames disappearing (sometimes)

Hi, I noticed something strange today. If I use computer modern unicode (the concrete font) together with Neo Euler math then sometimes function names (like \sin, \cos, \tan) disappear. Sometimes they show (in non-displayed math and in fractions(?)). Attached is a file showing the problem, together with the output and the typescript file. I use the latest ConTeXt version and I have cleared the cache, but no change. Maybe I'm overlooking something, but what? /Mikael