When setting Can Ever Affect Navigation to false, moving it, and then setting it back to true, the originally affected area remains, and it also creates a new affected area.
This occurs each time you move the object and toggle the setting.
Found in 4.12.5 CL 3039270.
Reproduced in 4.11.2 CL 2946394 and 4.13.0 CL 3106830.
Result: A new affected area of the Nav Mesh is created, and the old one still remains where the actor used to be.
Expected: The original area would be removed after setting Can Ever Affect Navigation to false.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-36033 in the post.