unfortunately it´s still not possible with Eclipse/PyDev. We also tried the python debug in VS2015 without any success.
FYI now found time to figure out how to attach to nx process to debug python files.
The key is to use Visual Studio 2017 with PTVS (python tools for visual studio) with the following description:
When you have opened the python scripts in Visual Studio and set your breakpoints you can jump into it by attaching to ugraf.exe process. Important is that the simulation has been started so that there is the python process to attach. You can see that in Type coloumn on ugraf.exe process Python, x64
I also tried a more lightweight way with Visual Studio Code and PyCharm but for any reasons I didn´t get it to work.
I had also some problems to define symbol files for debugging on another PC, where I tried to reproduce the installation steps to create a small step by step desciption. I didn´t get it to work too on this PC.
When I find more time I will create a small TechTip video.