I was actually just chatting with Tim from SmartThings about this, he looked over the code and everything seems right, so unfortunately it sounds like it’s an issue on your end. It seems like the options now are to either contact support and see if they can do anything on your end, completely remove Hue Advanced and all devices and set up again, or uninstall the SmartThings app from your phone and reinstall it.
I wish there was something else I could tell you, I know those options aren’t great. I would just start with whatever you think would be easiest based on your setup and work from there. Definitely let me know if you get it working.
EDIT: Do you only have the SmartThings app on one device? Is there any other device you could install it on to test?