MS coreutils: cp --reflink=always file1 file1_reflink1 returns "Not supported"

[lionelconswork]

Microsoft coreutils:
cp --reflink=always file1 file1_reflink1 returns "Not supported", on ReFS, WinBTRFS and msnfs41client

Steps to reproduce

$ cp --reflink=always file1 file1_reflink1
cp: failed to clone 'file1_reflink1' from 'xxx': Not supported