Does this look like cadence lock to you?

I've noticed when I'm running my heart rate seems to be very stable, obviously you expect it to go up and down with your pace and stable when you're holding the same pace. But it seemed to be absolutely stuck on 149/150 for a good part of the middle of that run. I also struggled to get it up into Zone 5 heart rate even when running at almost max pace. 1st pic shows heart rate and cadence. 2nd pic shows heart rate and pace. What do you think?