Track keepout near edge cut arc?

[der.ule]

Just to try to put all the post together:

What are these invisible traces?

I’m working on a board that started life on v4.7 and has been updated along the way as I have updated to the latest version of KiCAD (currently running 5.1.2). I recently needed to rework a section of the board and I was running into weird routing problems where is seemed like I was running into something invisible. I checked all the layers, and even removed all the footprints from entire sections, but nothing helped. Finally I changed the routing mode to highlight collisions, and low-and-beh…

KiCAD v5.1.2 - Router finds ghost circles where arc where used for the border