We have been having the same issue for months and always get the failed message. Clients we support are all in the local administrator's group, we have set the UAC to never notify. This is extremely frustrating especially when we are support multiple hosted clients, some with well over 100 users with locations throughout the US. We are having the user go through the fastsupport site as well as having them use the G2A-RS Customer Attended Support executable and are using version 3.1 Build 1251 with the same error.
What's really annoying is that many of our clients are using Citrix Storefront so this should be seamless.