Hi!
In our local Spine community we noticed that it is not possible to bake keys into the physics constraint in 4.3. I remembered that in 4.3.00-beta there was a new hotkey "key constrained" that allowed this. But now in 4.3.39-beta this hotkey does nothing and it is again impossible to bake keys.
We found a way around this problem by using a TK constraint on another bone and setting the keys there, but we still wanted to be able to always set keys directly for physically constrained bones.
Thanks!