I have same. Came after I moved messages between channels. This is an issue that bothers DiscourseHub every now and then. It was away quite a time but I reckon it came back after latest update of the app.
Sure, deleting an instance is one solution. I hate it because it breaks order of forums and I’m working on muscle memory 
It will go away after some time, on my forum it takes one week if I’m remembering right my settings.