Note 8 - Android 9.0 Upgrade issues - Bluetooth sleeping

[Android Central Question]

I have a medical app (Xdrip+) that talks to a Bluetooth blood sensor (Dexcom G6) On Android 8 OSes I was able to get readings normally. Now under Android 9.0, the OS seems to cut off or sleep the app's ability to use Bluetooth. It works normally if I leave the app open, but that's not why I have a phone, I would like to be able to use my phone or... you know... leave it on the table in front of me. If this doesn't work I don't get the data I need, and wind up with an unexpected low blood sugar. Is there a setting to tell Android 9.0 on Note 8 to behave and let the app do what it needs to do?

 

[tube517]

Have you re-paired the device?

Consider reset network settings. You would probably have to re-enter any wifi passwords but since this is a bluetooth issue, something to consider.

 

[Deke218]

Ensure the app isn't optimized in Device Care.

 

[William Nelson3]

Have you re-paired the device?

Consider reset network settings. You would probably have to re-enter any wifi passwords but since this is a bluetooth issue, something to consider.

I have re-paired the device. The app works normally, it just doesn't work when the app is off screen.

 

[William Nelson3]

Ensure the app isn't optimized in Device Care.

I did check this already, it is not optimized. I turned the entire device to high performance to check, to no avail.
Any other ideas?