My Health Recovery is changing depending on whether it's equipped in the 1st or 2nd weapon slot.
Equipped in 1st weapon slot = 37:

Equipped in 2nd weapon slot = 35:

Having no weapon equipped at all is the same as having one equipped in the 1st slot. These results are the same if I reverse the order of my weapons as well. (Same results with both my bow and 2H equipped, in either arrangement.)
And before people go blaming the AddOns, I'll remind them that they only retrieve the data from the server and display it, so there's no room for error. Regardless, I checked with the AddOns disabled as well and had the same results. You'll note that the "Health Recovery Idle" stat the AddOn also shows is affected by this bug as well.
I would also like to add that I was getting some messed up weapon animations while testing this. I'd have my 2H equipped and it used bow animations, and vice versa.