I'm on Polyphone 2.4.0 beta. Back in 2.3.1, it could easily drag & drop import 8-bit PCM WAVs no problem. Now, it reads them as 16-bit PCM and as such imports them incorrectly, resulting in a heavily biased, noisy, and unusable sample. Try with the attached, for example. I'm interpreting this as a bug since it was working fine in the last version.
Oops you are right. I fixed this issue with this commit and version 2.4.1 will import 8-bit wav samples correctly. I am checking first if other stuff needs to be included in this version. Thank you