Hello
I found a fix for this issue from: https://learn.pi-supply.com/make/fix-raspberry-pi-3-bluetooth-issues/
You only need the line
sudo usermod -G bluetooth -a pi
though as there's an issue with the default user permissions in the image
This same happened to me now. I tested the Tilt earlier and everything was ok. Now that the device is in the fermentor, I cannot get readings.
The hydrometer works with the Android app, and Bluetooth on the Pi works. They just don't work together!