This information pertains to Android devices only.

In the Android OS, apps must have Location Permissions in order to use the Bluetooth radio. While the permissions sounds like GPS use, it also includes network access.

When the Graphical Analysis, Graphical Analysis Pro, Instrumental Analysis, or Spectral Analysis apps are first launched they request permission to access the device’s location. If the user taps Deny, along with the “Don’t ask again.” option, the apps will silently fail to reach the Bluetooth radio, even though the radio is on and available to other apps.

The apps cannot distinguish between the radio being off and location permission denied, so the error message shown may be due to either problem.

To turn on Bluetooth, swipe from the top of the screen and tap the Bluetooth icon until it is enabled.

To make sure the device has the location permission on, swipe down from the top of the screen and tap the gear icon. Under Security and Location, tap Location and make sure it is turned on.

To give specific apps location permission, swipe down from the top of the screen and tap the gear icon. Under Apps, find and tap the appropriate app. Locate the permissions item, and tap to reach a screen where Location permission can be granted.

Why is Graphical Analysis for Android requesting permission to see my location?
Graphical Analysis says that Bluetooth is not enabled, but I am sure it is on. (macOS 11, iOS/ iPadOS 13 and newer)
Troubleshooting Bluetooth Connections with Go Direct Sensors