As of 0.6.1, Zook Man ZX4 (and its English "translation", Rockman & Crystal) closes the emulator after the GBA start-up screen (or it just closes instantly if the BIOS is not present/is skipped). This issue is not present in 0.6.0, so it's likely a regression.
EDIT: Same thing happens on the latest interim release (dated 2018-09-10).