Cheat engine vs. PPSSPP

[Mech_91]

I tried to use Cheat Engine to hack Ace Combat: Joint Assault for more points during the mission, found 3 values (one 2-byte, one 4-byte, and one 8-byte), but when I try to change any of them, the value changes to ?? and emulator crashes. What could be wrong?

PPSSPP version is 1.10.3.