Hi, there’s some corrupt blueprint somewhere in the workshop, among the popular structures. We don’t know which, so you have two options.
Unsubscribe each of your workshop items 1 by 1, and find out which one caused the issue. If you find out, please let us know. It would be awesome if you did this.
Unsubscribe to all at once. This will fix it, but you won’t know which structure caused it.