Engrave sketch of letter E

[99mandolins]

If I do a simple sketch of a capital letter E with four lines and try and engrave it, it works if the step down is the same as the depth, but one line goes wrong if I change the step down to 1.
I'm using
OS: Manjaro Linux
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15900 (Git) AppImage
Build type: Release
Branch: master
Hash: a73b10203ab1cb31df4a8763b050d64da8e81580
Python version: 3.6.7
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/Ireland (en_IE)

Great program by the way!