I've run into this once before. If I recall, it was some incompatibility between either older firmware (on the M1 or XEP) and/or the version of RP2 that I was running. Until I figured that out, I just went to the Elk web site and manually downloaded the latest firmware and then did an update.
What levels of firmware do you have on the M1 and XEP? What version of Windows are you running?