There have been no upgrades to Moto G4 Plus device for one device that I have. The other one got upgraded to Oreo 8.1, but this one just refuses.
Diagnostic checks included, Wipe Cache, Factory Reset, and all, but to no avail.
Later, using Lenovo’s Moto Smart Assistant from this link, https://support.lenovo.com/in/en/downloads/ds101291 the update did not happen. Error was related to ro.carrier being unknown. The normal value for ro.carrier should be ‘retin’.
Anyway, phone bootloader was never unlocked. It suffered from Ghost Touch, and was given to the Motorola service center for repair. No idea, if anything was done at that time.
Now, to visit the service center to get them to do the upgrade to Oreo 8.1.