You need to point to the game executable so for the Steam version it should be:
[YourSteamInstallLocation]\SteamApps\common\Elite Dangerous\Products\elite-dangerous-64.exe
Close enough 🙂 The executable is at C:\Program Files (x86)\Steam\steamapps\common\Elite Dangerous\Products\elite-dangerous-64\EliteDangerous64.exe
In C:\Users\tage\AppData\Local\Tobii\Tobii InfiniteScreen\Content\Settings\EliteDangerousApplication\HidMapperSettings this is stored as <InstallLocation>C:\Program Files (x86)\Steam\steamapps\common\Elite Dangerous</InstallLocation>.
Most likely due to how Frontier “merged” the two game versions I have multiple directories with related names. E.g. C:\Program Files (x86)\Steam\steamapps\common\Elite Dangerous Horizons and C:\Program Files (x86)\Frontier\EDLaunch as well as the above directory. I never purchased “bare” ED, just ED:H after its launch, but now the main game executable lives in the ED directory rather than the ED:H one. I hope this is not a problem given the HidMapperSettings file. Also, EliteDangerous64.exe only exists in one single place.
I have proof-read and copy-pasted the above path and file names. Does ISE expect anything else than the above?
Also: the file modification date of the files in C:\Users\tage\AppData\Local\Frontier Developments\Elite Dangerous\Options\Bindings do not change even when I uninstall and reinstall ISE. Is this a problem? The Custom.1.8.bind file was modified when I installed ISE for the first time (though that may have been a pre-freetrack-fo-ED version of ISE). Nothing happens on disable/re-enable ISE for ED either. Is this expected behaviour?