Keyword Recogniser not working in build

I have a game that uses voice control and up until now it's been working fine. For some reason the keyword recogniser will no longer work in the built game. It still works fine in the editor. What could cause this?

I'm using Unity 2017.2 but i also have the same bug if i build with 2018 beta.
I've checked that the keyword recogniser is started and listening, and it is. No errors either, it seems to be fine but for whatever reason just will not recognise words

On a related question. Is there a way to assign a specific recording device to the recogniser? I can get a list of the devices but which one is used seems to be handled automatically

 

Thanks for the quick reply. Yes the capability is enabled and working, and it's there in the app manifest. I have a mic set up process at he start of the game and it still asks for mic permission and reports that it's running correctly. Just wont recognise anything.

 

For anyone getting this. The problem is in UWP, the first voice recogniser created in unity will ask for permission to use the mic, but won't work until the game is restarted and it already has permission so doesn't ask. The workaround was to use a dummy recogniser to prompt for permission and then create a second voice recogniser after the first obtains the permission.