OK Google not working on many devices
In appears that the ‘OK Google’ voice command is not working on some Android devices. The options to turn on voice command in the Settings menu is also inaccessible. Google has responded to many complaints and has said that it is working on resolving the issue at hand.
Whenever a user tries to activate Google Assistant using the ‘OK Google’ voice command, they will be asked to activate voice match. If the user tries to do that, the system will notice that the voice is already registered on the device, and the user is put in a dead end. In the Google Settings options where users could enable the hotword detection, the two options are greyed out and made inaccessible. Users have also complained to Google on Twitter and a Reddit thread is active as well apart from the Google Assistant help forums.
Devices that are experiencing this problem include the Xiaomi Mi A1, OnePlus 5, OnePlus 5T, Xiaomi Mi Mix etc. Google representatives have acknowledged the issue and confirmed that it has been escalated to the team concerned. A fix should come out soon. Google has listed a workaround on the forums whereby users need to uninstall the latest update for the Google app. You can see a step by step guide for this process here.