Edeliver set version is not working

I am trying to set custom version while generating a build using edeliver. Well it successfully does create a build(its not proven though, I just see a success msg in console) when I provide RELEASE_VERSION option but it wont copy release in my local releases folder. But if I dont provide RELEASE_VERSION, it will successfully generate build and copy to my releases folder. Please have a look at screenshot below.

example command I use: RELEASE_VERSION="api_0.1.5" mix edeliver build release

Any help what I am missing here would be great. Thanks in advance

–set-version is also not working