Just tested with wavpack 4.5 & it worked too, here is my 3 settings for Tak/Flac/Wv:
Encoder: c:\windows\system32\cmd.exe
Extension: lossy.tak
Parameters: /d /c c:\z\lossywav - --portable --silent --stdout|c:\z\Takc -e -p3 -fsl512 -ihs - %d
Format is: lossless or hybrid
Highest BPS mode supported: 24
Encoder: c:\windows\system32\cmd.exe
Extension: lossy.flac
Parameters: /d /c c:\z\lossywav - --portable --silent --stdout|c:\z\flac - -6 -b 512 -f -o%d
Format is: lossless or hybrid
Highest BPS mode supported: 24
Encoder: c:\windows\system32\cmd.exe
Extension: lossy.wv
Parameters: /d /c c:\z\lossywav - --portable --silent --stdout|c:\z\wavpack -hm --blocksize=512 --merge-blocks -i - %d
Format is: lossless or hybrid
Highest BPS mode supported: 24
wavpack works but even with --merge-blocks its efficiency seems reduced compared to real lossless source, for exemple on my single test album flac -6 compressed more than wavpack -h on this lossywav file while according to my experience wavpack -h usually beats flac -6 on real lossless music.
also when I tried to add --keep-foreign-metadata to the flac command line, it crashed.