That fixed it. Upon launch, after deleting both ~/Library/Containers/Newsblur and ~/Library/Group Containers/group.com.newsblur.NewsBlur-Group, I see the login screen.
I kinda got the vibe that it was a corrupt preference (or something similar), but didn’t know where to look.
p.s. long time subscriber here… definitely appreciate your time and efforts making and maintaining NB. 