Please move to the Lightroom forum.
Yeah, this problem started with LR 5.5 and continues with LR 5.6 if you didn’t fix it for LR 5.5.
The issue is that the SLCache folder that holds the licensing info is corrupted or unavailable, somehow, so you have to delete the contents or at least fix the permissions on it. I have deleted the contents without deleting the folder and it works after that, although other Adobe apps, like Elements, need re-licensed with their serial numbers, so be prepared for that. Here is the Adobe help page about it:
Thank you. Everything back to normal.