When you have a sub level with some level transform, changing its visibility then doing undo makes the sub level moved away as if the level transform applied twice.
I could repro the issue in 4.13.2 and 4.14.0.
1. Open LevelTransformUndo project. This contains a sublevel with a cone, with +Y level transform applied.
2. Open Levels window
3. Set the sublevel's visibility off
4. Undo(Ctrl-z)
5. Thr sublevel is now moved away further in Y axis
7. You can repeat 3-4 to see the sublevel go even further away
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-38873 in the post.