I reckon it's a BT limitation, as my experience is BT gets...

I reckon it's a BT limitation, as my experience is BT gets really cranky when my dense body or head gets in the way of the signal path between my SGS7 and any of my plantronics backbeat, fortis gearfit, blueant thingy and even the office's soundbar (15m away and BT is perfect until someone walks in between.) This (anecdotally) started being the trend when my BT earpieces starting being A2DP devices for my music - I never really noticed BT dropouts for just call audio profile (probably cell dropouts were more noticeable and prevalent back then.)
That's probably the main reason NFC between the IQBuds - BT transceiver by the way is in the left IQBud - keep the smartphone more to your left side, and it might improve things..