Yes, I'm having the same trouble. HRM pairs when Leikr initially turned on, then Leikr stops receiving data from HRM once I start my workout. Fresh battery in HRM, fully charged battery in Leikr.
I emailed team Leikr about it, they suggested it might be the wi-fi signal interfering with the ANT+ signal. I thought it might be unnecesary to have the wi-fi enabled when working out, that it should only turn on when Leikr is initialized so it can look for the GPS assist, then turn off again until the user conducts a sync at the end of the workout.