Broadcasting wrong HR... kind of.

So after recent changes whare the watch no longer turns off the on board HR sensor -> when it has HR band connected (be it polar or HRM), this is kind of bad. 

Previously when i have used my watch to transmit HR to garmin edge - Whilst watch was getting HR from HRM chest strap, all was ok.

But yesterday (i don't normally use cheststrap) when i have used that, watch was still broadcasting it's own HR from onbard sensor, even when it had HR strap connected.

How i know, well watch was showing HR from HRM strap on it's display, but edge connected (normally) to watch as few months ago, but both displays were showing different HR values, ie watch was showing HR from strap, but Edge was showing HR from watch sensor -> how do i know well, i've literally took watch off my wrist and Edge device showed no HR values, but watch was still showing HR values from strap.

Is there a way to disable this behaviour and have watch broadcast HR (from cheststrap - if one is used).

Thank you