I am sure there were plenty of such failures. I have read of many.
However, those engines likely had a flaw, a manufacturing defect or something that had developed later. In AH we are given new, "perfect" aircraft for each sortie.
Nobody wants to be having a furious fight in their P-38 against a Ki-84, finally, in a spiral climb, approaching a gun solution only to have the random number generator decide that their #2 engine just conked out. Ki-84 spirals up, then comes down and kills the P-38. Sure, the Ki-84 pilot, not even knowing the P-38 suffered an engine failure, may think it was a great fight. Do you think the P-38 pilot will think so? He won't feel like the Ki-84 pilot beat him, he'll feel like the random number generator beat him.