Hello,
Steam version of EVGA Precision XOC 6.1.13 OSD wasn't working in Skyrim Special Edition so I did some investigation ...
The standalone 6.1.13 XOC OSD was working though.
Tried many things like complete uninstall the steam version and wipe all installation directory with no luck.
What is happening is that I'm having windows 10 x64 and when Precision XOC (steam version) was loaded, the 64bit version was on.
I noticed that the EVGA PrecisionX Server 6.1.9 that was loaded (when I activated OSD) was the 32bit.
I run the 64 bit version manually from 
(C:\Program Files (x86)\Steam\steamapps\common\EVGA PrecisionX\PrecisionXServer_x64.exe)
and both were running and OSD worked in game.
 
Seems that every time you activate the OSD button, calls the 32bit version and since Skyrim SE is 64bit, needs the 64 bit version of PrecisionX Server
It may work for any 64 bit games that OSD isn't working.
 
P.S.: I changed also the *.exe files in Precision folder to run as administrator (PrecisionX.exe - PrecisionX_x64.exe - PrecisionXServer.exe - PrecisionXServer_x64.exe)