What changes did you make?
I don’t understand how you had it set up to begin with that caused your issues–if you want us to fix something, that needs to be clearer.
If you import an audio file into UE4 as of 4.22, it will automatically convert your file to a 16-bit Wav file. We support any samplerate you wish, though commonsense samplerates should be employed. We support Mono, Stereo, Quad, 5.1, and 7.1 file import–and you don’t need to import them as a group of mono files–that was a very old method from before we had audio programmers.