Master's Gift doesn't multiply HP, though.
Oh yeah, you're right. I had it in my head that "it multiplies 3 stats" and forgot Block Strength was a stat, sorry.
I'll definitely look at Heartbeat later. It shouldn't be a HUGE deal (the most impact I can see it having is setting up Perilous Punch strats), but I expect it's probably related to the underlying code. Now that my coding skills have improved, I could probably fix it given some time.