Resampling misbehaving?

In Windows 8.1, using both 2.2.2 and 2.3.1 resampling is not behaving correctly, by my understanding - or am I missing something obvious? Many years ago I tested the ability of Audacity to perform upsampling without adding artifacts, and it performed admirably - now it’s adding amplitude distortion at the top end of the frequency band.

Audio at 44.1k which has content above about 20kHz does not have the latter resampled correctly - if one upsamples and downsamples a track, and differences the final from the original, a major spike glitch occurs in the 20KHz area - Audacity can’t be used to verify the accuracy of other processing; something I used to regularly do.

Please give step by step instructions to reproduce the issue. Ensure that you include any non-default settings / Preferences that you are using.

Should have replied earlier, but resolved that the issue was to do with the resampling routines from the SoX library - confirmed that SoX from the command line did the identical thing, and this was because of the bandwidth parameter. I don’t know whether it makes sense to pursue it further, but I used a workaround of brickwalling all frequencies above 20kHz, which gave me satisfactory behaviour for what I was trying to do,

Thanks for the reply.