I also have this problem with prime Intel 4200M, Geforce GT 740M using the nvidia 390 driver, on 18.10 (cosmic).
Nouveau works, and the intel gpu also works even if I have the 390 driver installed (I used: sudo prime-select intel)
I also have this problem with prime Intel 4200M, Geforce GT 740M using the nvidia 390 driver, on 18.10 (cosmic).
Nouveau works, and the intel gpu also works even if I have the 390 driver installed (I used: sudo prime-select intel)