Ok, it appears to work for me under MorphOS aswell.
My guess is that you forgot -noixemul and that you have some old and incompatible ixemul.library installed.
Try adding -noixemul if you didn't already.
Another option: You have some weird libnix stdio that uses dos.library Printf or exec.library RawDoFmt for printf. dos and exec don't know about %f...
