I bought a Nokia 8 (TF-1012) specifically as it had advertised ANT+ support.
However it arrived with Android 8.1 Oreo which seemed to be missing the ANT Firmware. Customer support was of no use, as was returning the phone to a Nokia service center who simply sent it back to me.
If you have downloaded ANT Radio service and ANT+ Plugins, yet the built-in firmware is not activated and you see a screen like this in ANT Tester (ANT USB is not required), follow the instructions below:
1) Go to Apps & Notifications -> See All Apps
2) Select 'ANT Radio Service' (If you cannot see this app, you need to download it from the Google play store)
3) Select Permissions
4) App Permissions
5) Slide switch to allow ANT
6) Check in ANT Tester - Success!!!
It seems that there is a similar problem on Nokia 6 running 8.1:
and also on Pie:
again, on Pie: