I'm an advanced IT student, and happen to be very experienced in Nvidia,
I strongly recommend you to remain using the Geforce Exerience, since they update the graphics card whenever a new update comes out (it does prevent corruption in engine failure with graphical programs)
Secondly, make sure that (if you're not on a laptop) your computer has disabled the Intel "graphics card" since this should have automatically disabled by your system (motherboard) as it is a strict policy that the system is not allowed to use both hardware pieces at the same time (i could explain it to you, but that would mean i'd own the website in size of explanation).
Even though this might seem odd to you, changes are 90% that the issue lays with ETS2 creating a session that "disallows" the Geforce Experience into working properly.
Try reinstalling All required software, drivers, and make sure to check for any drivers that might make you feel like they are the cause of it (don't worry, uninstalling such won't harm a soul)
And last, if non of the above works, make sure to press start key + R, type eventvwr, go to applications & Services Log, and check for any errors related to Nvidia or ETS2
Goodluck, and if any questions make sure to reply to this post.