Watch keeps connecting and disconnecting from External HRM

This bug has been irritating me since a while. When we connect the watch to an external hrm, it displays the external heart rate for a while...now here is the issue that keeps on happening. The watch automatically shifts to optical sensor after a few seconds. Then when I go in the sensor menu, I see that its searching for the external hrm and then it connects to it and stays connected only till I am in the Sensor menu. Once I am back on main screen, again the watch disconnects from external sensor.

This is so ridiculous, the option of disabling or enabling the use of the external sensor, should be upto me rather than the watch, the watch should be continuously connected to the external until n unless I disable it. 

It stays connected only during an activity or when I am in the sensor menu.