UE4 will import 16 bit PCM .wav files up to 48khz sample rate; maybe check the properties of the .wav file and make sure it’s in this format?
Best-
Zak
As a general tip, heed warnings and follow up what they tell you to do. If it tells you to check the output log, go check it. Nine times out of ten it’ll tell you what went wrong. It’s particularly useful for diagnosing errors like this.