AP_NavEKF2: Only allow rangefinder height option during optical flow nav

libraries/AP_NavEKF2/AP_NavEKF2_PosVelFusion.cpp

@@ -544,7 +544,7 @@ void NavEKF2_core::selectHeightForFusion()
     baroDataToFuse = RecallBaro();
 
     // determine if we should be using a height source other than baro
-    bool usingRangeForHgt = (frontend->_altSource == 1 && imuSampleTime_ms - rngValidMeaTime_ms < 500);
+    bool usingRangeForHgt = (frontend->_altSource == 1 && imuSampleTime_ms - rngValidMeaTime_ms < 500 && frontend->_fusionModeGPS == 3);
     bool usingGpsForHgt = (frontend->_altSource == 2 && imuSampleTime_ms - lastTimeGpsReceived_ms < 500);
 
     // if there is new baro data to fuse, calculate filterred baro data required by other processes