One thing we noticed over in Mismatch nested and parent city - #2 by hans1 is that the service I use to collect OSM data seems to have several servers behind a load balancer - so, a request into their service may be routed to one of several servers … and that not all the servers have their data fully updated and each of the servers could be on a different date.
So Monticello probably got an update sometime after you created the streets (on/after the 3rd, it looks like) … then that update on the 10th may have reached a server that was using data from e.g. September 2nd (a day before your edit). This would have caused it to see the data as deleted & update the CityStrides database accordingly.
This hasn’t been much of an issue up until now, so I’m going to hold off on taking any action. It’s possible that it’s not common/expected for their servers to become so off sync.