Do you have the driver installed? If the U-1 is always in read-only mode, how do you write from Vegas? Are you working from multiple systems?
Latest driver can be found here:
https://www.servicesplus.sel.sony.com/sony-software-model-PDWU1.aspx
Afterwards use the bundled utility app to upgrade the firmware on the U1 (firmware is included with the utility; you don't need to download anything else).