During a Reality Fracture Premier Draft match, I controlled
Danitha, Spear of Agony.

I cast Memory Trap targeting a creature controlled by my opponent.

Danitha, Spear of Agony did not trigger and did not receive a
+1/+1 counter.

According to Danitha's card text, its ability triggers whenever
I cast a spell that targets an opponent or a creature an opponent
controls.

Memory Trap was cast targeting a creature controlled by my
opponent.

Expected behavior:
Danitha should trigger when Memory Trap is cast and receive a
+1/+1 counter before Memory Trap resolves.

Actual behavior:
Danitha did not trigger and no +1/+1 counter was placed on it.

This occurred during a Reality Fracture Premier Draft match on
MTG Arena.