I've had a lot of grief with the scanning API of late.
There is no way to monitor it from the API side that I am aware of. All you can do is to make sure that you keep receiving more data.
I've had a couple of nasty ones recently where the scanning API stops sending data. Deleting the config in the dashboard and putting it in again does not fix it.
The last one took support 2 or 3 months to resolve. They wont say that they did to fix it. And now I have another one that it has happended to.
My will is being sucked away.