Not sure if this is a bug or a configuration setting that has changed and I have not updated. Before I could use the AI in help. Now for anything I type in I get “The data couldn’t be read because it isn’t in the correct format.”
In my case, Help sometimes opens and works normally. But if I close the window and then try to open it again some time later because I need to look something up, DT simply doesn’t open anything. And it’s not just Help: the first three other items in the Help menu — Extensions & Bookmarklets, Hidden Preferences, and Release Notes — won’t open either.
The only way I can access any of those options again is to quit and restart DT, although sometimes even that doesn’t fix the problem.