So it’s been a while since I shared that the QA team had been able to identify the cause. I just wanted to offer an update -
The code changes that are needed for this fix are under review. There are elements of the change that are part of the login flow for a character, so the team is being very careful about what they change and how thoroughly it gets tested. There are also other high impact bugs that may get priority with the QA team so I’m still not able to offer an ETA.
Make sure you’re watching the official Hotfix blog. It will likely be covered there when the fix is released to the live service.