ATC;
Allegedly there were rumblings early on that the 777x was using the same software (FCS) from the 777, so hard to say what's going on as all this Boeing proprietary information.
I believe that most of the software for updates and patches is "offshore" so it will take time for the lab test and subsequent install of patches.
Could be that an update broke an existing install, but that is as far I would like to go until the facts (if released) are known.