What is Windows host file encoding? Is it UTF-8? Or is the ASCII + system code page? How should I add IDN records (international domain names with umlauts, etc.) And can they be added at all?
It must be ANSI or UTF-8 without specification. I was just dealing with a server on which the host file encoding was installed in UCS-2 Little Endian, and this led to ignoring the file.
There is a lot of information: https://serverfault.com/questions/452268/hosts-file-ignored-how-to-troubleshoot