APK password signing error on windows, fine on OSX

I've been working on a game on my mac for about six months, it's signed and uploaded to a beta channel on the google play store. I've moved the project over to my windows 10 machine and I'm getting the follow errors when i build:

 CommandInvokationFailure: Failed to build apk. C:/NVPACK/jdk1.8.0_77\bin\java.exe
 -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:/Users/Admin/AppData/Local/Android/sdk\tools"
 -Dfile.encoding=UTF8 -jar "C:\Program Files\Unity
 5.5.0\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -
 stderr[ Error: Invalid password for key 'beta' ]

I'm using unity 5.5.0f both on windows 10 / osx 10.12.5. I've also built other apps from the windows 10 machine, signed and ready for the app store also without problem. On the problem project i'm copy pasting the keystore/alias passwords in from the same text file I store them in on mac, watching very carefully to make sure i'm copying without whitespaces etc. For testing I've even created a brand new android project on windows 10 with it's own keystore and it signs the build fine.

Any clues to why this particular keystore doesn't work here?