To distribute the app to our testers we use Xcode, which we do using the following process:
XC Ad Hoc
I was facing same issue, resolved using command line "xcodebuild" tool script, which is preinstalled with XCode6 (didn't need to re-install XCode5).
Script in terminal:
xcodebuild -exportArchive -archivePath $projectname.xcarchive -exportPath $projectname -exportFormat ipa -exportProvisioningProfile 'Provisioning Profile Name'