Just my 2 cents, in the form of my recent experience:
At first, I couldn’t get my Eyex to work in Elite (non Steam version). Then I discovered there was a Steam version of Elite and decided to give it a try to get rid of the boring launch/update/wait cycle. So I grabbed my Steam key on Elite site.
Lo and behold ! Eyex worked perfectly in the Steam version of E:D.
As an added benefit it now works in both versions (Steam/non Steam) !?!?!?
No idea why that happened.
In ARMA3 and other Bohemia games I had to manually edit my config files to set a parameter (Freetrack=1), maybe installing the Steam version modified my E:D config or installed a new version of an outdated component.
Still trying to get Eyex to work in DCS.