Don’t know if you solved this but I call Convolution’s prepare() method before its loadImpulseResponse() method. You can also load your .wav in as a binary and use that as the sourceData parameter for the implementation of the loadImpulseResponse() method that requires sourceData and sourceDataSize like so:
juceConvolution.prepare(spec);
juceConvolution.loadImpulseResponse(BinaryData::OutbackClimbingCenter_wav, BinaryData::OutbackClimbingCenter_wavSize, true, true, 0, true);