11760|Freeze when editing in external editor

I’m having an issue with text editor based changes inside parameters.
If I alt-e on a parameter set to be in expression mode, change the parameter values in either Notepad++ or SublimeText3, Touch freezes, while changing the parameter field back to a constant. I can quit and save, but I can’t do anything in the interface.

I wonder if this has anything to do with my cut/paste issue reported previously.

Update : If I remove the env var and Touch reverts to using Notepad as a default, it all works well.
This is after uninstalling Touch and installing 11760 as a fresh install