Can't open Google Assistant settings
I had the same problem on multiple Huawei phones. The only thing I have found to work is a factory reset. You can back up your phone first if you have anything you want to save, but I've only gotten it to work with a full reset of all data. When I restore the backup, sometimes it stops working again, sometimes it doesn't. I think it's a problem with the EMUI skin, because I have had no problems with it on custom ROM's on Huawei devices. Hope you get it working!