Since v5.1.1 the button "Bind Layer" is missing from the Tool options bar when using the bind layer tool, I can still bind the layer by pressing spacebar.
I think there's some confusion here. There never was a "Bind Layer" button, and pressing the spacebar never was a way to bind a layer to a bone. You need to click on the bone with the mouse to bind a layer to it.
Are you maybe talking about a different tool than the Bind Layer tool?
