nRF_UART connects to some phones and not others

Question

Hi I'm using Android Studio 3.2 and github.com/.../Android-nRF-UART My Samsung SM-G570Y (Android 7.0 API 24) works no problems but the Samsung SM-G955F (Android 8.0.0, API 26) fails to connect. the message on the phone says Device: Connecting Device: Not Connected any ideas as to why it is failing? 
 attached is the Debugger console output, any ideas as to why it is failing? 
 D/BluetoothAdapter: stopLeScan() D/BluetoothAdapter: STATE_ON D/BluetoothAdapter: STATE_ON scan not started yet D/ViewRootImpl@dd3f820[MainActivity]: ViewPostIme pointer 0 D/ViewRootImpl@dd3f820[MainActivity]: ViewPostIme pointer 1 D/nRFUART: onPause D/DeviceListActivity: onCreate D/DeviceListActivity: populateList D/BluetoothAdapter: startLeScan(): null D/BluetoothAdapter: STATE_ON I/chatty: uid=10430(u0_a430) com.nordicsemi.nrfUARTv2 identical 4 lines D/BluetoothAdapter: STATE_ON D/BluetoothLeScanner: Start Scan with callback D/BluetoothLeScanner: onScannerRegistered() - status=0 scannerId=10 mScannerId=0 D/ViewRootImpl@5e7c7df[DeviceListActivity]: setView = DecorView@8103c2c[DeviceListActivity] TM=true MM=false D/ViewRootImpl@dd3f820[MainActivity]: MSG_WINDOW_FOCUS_CHANGED 0 D/ViewRootImpl@5e7c7df[DeviceListActivity]: dispatchAttachedToWindow V/Surface: sf_framedrop debug : 0x4f4c, game : false, logging : 0 D/ViewRootImpl@5e7c7df[DeviceListActivity]: Relayout returned: old=[0,0][0,0] new=[160,284][1280,904] result=0x7 surface={valid=true 543887429632} changed=true D/mali_winsys: EGLint new_window_surface(egl_winsys_display *, void *, EGLSurface, EGLConfig, egl_winsys_surface **, egl_color_buffer_format *, EGLBoolean) returns 0x3000, [1120x620]-format:1 D/OpenGLRenderer: eglCreateWindowSurface = 0x7eadffcbb0 D/AbsListView: in onLayout changed D/ViewRootImpl@5e7c7df[DeviceListActivity]: MSG_RESIZED_REPORT: frame=Rect(160, 284 - 1280, 904) ci=Rect(0, 0 - 0, 0) vi=Rect(0, 0 - 0, 0) or=1 MSG_WINDOW_FOCUS_CHANGED 1 V/InputMethodManager: Starting input: tba=android.view.inputmethod.EditorInfo@74736f5 nm : com.nordicsemi.nrfUARTv2 ic=null I/InputMethodManager: startInputInner - mService.startInputOrWindowGainedFocus D/ViewRootImpl@5e7c7df[DeviceListActivity]: Relayout returned: old=[160,284][1280,904] new=[160,284][1280,993] result=0x21 surface={valid=true 543887429632} changed=false D/OpenGLRenderer: eglDestroySurface = 0x7eadffcbb0 D/mali_winsys: EGLint new_window_surface(egl_winsys_display *, void *, EGLSurface, EGLConfig, egl_winsys_surface **, egl_color_buffer_format *, EGLBoolean) returns 0x3000, [1120x709]-format:1 D/OpenGLRenderer: eglCreateWindowSurface = 0x7eadffcbb0 D/AbsListView: in onLayout changed V/InputMethodManager: Starting input: tba=android.view.inputmethod.EditorInfo@6214d71 nm : com.nordicsemi.nrfUARTv2 ic=null I/InputMethodManager: startInputInner - mService.startInputOrWindowGainedFocus D/ViewRootImpl@5e7c7df[DeviceListActivity]: Relayout returned: old=[160,284][1280,993] new=[160,284][1280,1150] result=0x21 surface={valid=true 543887429632} changed=false D/OpenGLRenderer: eglDestroySurface = 0x7eadffcbb0 D/mali_winsys: EGLint new_window_surface(egl_winsys_display *, void *, EGLSurface, EGLConfig, egl_winsys_surface **, egl_color_buffer_format *, EGLBoolean) returns 0x3000, [1120x866]-format:1 D/OpenGLRenderer: eglCreateWindowSurface = 0x7eadffcbb0 I/zygote64: Compiler allocated 4MB to compile void android.view.View.<init>(android.content.Context, android.util.AttributeSet, int, int) D/AbsListView: in onLayout changed D/ViewRootImpl@5e7c7df[DeviceListActivity]: ViewPostIme pointer 0 D/ViewRootImpl@5e7c7df[DeviceListActivity]: ViewPostIme pointer 1 D/AbsListView: onTouchUp() mTouchMode : 2 D/BluetoothAdapter: stopLeScan() D/BluetoothAdapter: STATE_ON I/chatty: uid=10430(u0_a430) com.nordicsemi.nrfUARTv2 identical 2 lines D/BluetoothAdapter: STATE_ON D/BluetoothLeScanner: Stop Scan with callback D/BluetoothAdapter: stopLeScan() D/BluetoothAdapter: STATE_ON D/BluetoothAdapter: STATE_ON scan not started yet D/ViewRootImpl@dd3f820[MainActivity]: MSG_WINDOW_FOCUS_CHANGED 1 V/InputMethodManager: Starting input: tba=android.view.inputmethod.EditorInfo@6744e48 nm : com.nordicsemi.nrfUARTv2 ic=null I/InputMethodManager: startInputInner - mService.startInputOrWindowGainedFocus D/ViewRootImpl@5e7c7df[DeviceListActivity]: MSG_WINDOW_FOCUS_CHANGED 0 D/nRFUART: ... onActivityResultdevice.address==DF:61:DF:F2:AC:C1mserviceValuecom.nordicsemi.nrfUARTv2.UartService@64ef1d6 D/BluetoothGatt: connect() - device: DF:61:DF:F2:AC:C1, auto: false D/BluetoothAdapter: isSecureModeEnabled D/BluetoothGatt: registerApp() registerApp() - UUID=4999e726-7890-481d-9099-ecfa9654b944 D/UartService: Trying to create a new connection. D/BluetoothGatt: onClientRegistered() - status=0 clientIf=10 D/nRFUART: onResume D/OpenGLRenderer: eglDestroySurface = 0x7eadffcbb0 D/ViewRootImpl@5e7c7df[DeviceListActivity]: Relayout returned: old=[160,284][1280,1150] new=[160,284][1280,1150] result=0x5 surface={valid=false 0} changed=true D/BluetoothAdapter: stopLeScan() D/BluetoothAdapter: STATE_ON STATE_ON scan not started yet stopLeScan() D/BluetoothAdapter: STATE_ON STATE_ON scan not started yet D/ViewRootImpl@5e7c7df[DeviceListActivity]: dispatchDetachedFromWindow D/InputEventReceiver: channel 'd9efc54 com.nordicsemi.nrfUARTv2/com.nordicsemi.nrfUARTv2.DeviceListActivity (client)' ~ Disposing input event receiver. channel 'd9efc54 com.nordicsemi.nrfUARTv2/com.nordicsemi.nrfUARTv2.DeviceListActivity (client)' ~NativeInputEventReceiver. D/BluetoothGatt: onClientConnectionState() - status=133 clientIf=10 device=DF:61:DF:F2:AC:C1 I/UartService: Disconnected from GATT server. D/nRFUART: UART_DISCONNECT_MSG W/UartService: mBluetoothGatt closed D/BluetoothGatt: close() D/BluetoothGatt: unregisterApp() - mClientIf=10 D/BluetoothAdapter: stopLeScan() D/BluetoothAdapter: STATE_ON D/BluetoothAdapter: STATE_ON scan not started yet