Hi hi! So I was laying down fiber cable in the game, and figured out how to replicate-ish the bug to a certain extent. I was working on a new level 10 region when I decided to put down a Capacitor, instead of an Uplink, in the center of the region since the Uplink in the neighboring one was new, and still had a lot of capacity to give. I laid down fiber connecting the Uplink to the new Capacitor, across regional boundaries, and immediately, the new fiber connection became untargetable. I could not connect new fiber or regular cable to the fiber connection between the Uplink in one region, and the new Capacitor in the new region.
And then, when looking for other regions where this bug affected the fiber connection, I stumbled upon a slightly-olderish regional connection, also between an Uplink and a Capacitor, with the fiber connection going across regional boundaries. The quirk about this instance of the bug, is at a certain point in the connection, the fiber connection is targetable, so I can branch new regular cable or fiber off from the fiber line between the Uplink and the Capacitor. However, a large part of the fiber connection is untargetable, just like the newly laid connection in my newest regions, per the above.
In the screenshots, I have defined the regions where the fiber cable is connecting to the Capacitor, as BUG REPORT REGION A and BUG REPORT REGION B. I will attempt to upload the save file.
Thank you for the assistance Dev Team! This game is awesome!