C17 7.21.6.2p16 returns EOF only if input fails before the first conversion completes, and a suppressed conversion completes. FreeBSD counts it in nconversions (vfscanf.c, releng/11.4, lines 799-805). The host scanf returned EOF there, so sscanf("12", "%*d%d", &v) reported EOF instead of 0. Each suppressed conversion now records its end with a %n and a result of EOF becomes 0 when one was recorded.
Hussein Kadhim
Ethan Barr
SamG-Coder