How to make CTRL-C work in command line when it does not?

I'm struggling with not working CTRL+C in a certain environment shell command line (CentOS 7 / Vagrant guest of Windows host). I use bash there. The OS, seem, does not matter. Example run sleep 1000 and press the ctrl-c:

$ sleep 1000
^C^C^C

So, it's typing ^C and that's it. ^C is bound for the interruption.

$ stty -a
intr = ^C; ...

How to *make* it work? In the following post, where I was inspired to fix it, the answer explains a lot but does not give a simple answer on how to make it work.
https://unix.stackexchange.com/questions/92562/why-didnt-ctrl-c-work
It seems it's a simple thing that I'm struggling with.