Brush settings lock forces uniformity of all brushes

I was hoping I could use the brush settings locks to hold temporary tweaks constant as I switch among different brushes. But what’s happening is that if I lock Shape Dynamics for one brush, it is locked for ALL brushes. If I then change the minimum diameter percentage for one brush, all brushes are set to that same percentage. And, yes, I am switching among brushes, presets, not brush tips.

I’m pretty sure it’s not supposed to work this way, but I’ve already downgraded from v 26 to v 25.9.1, deleted MRUBrushes and Brushes.psp, and done a command-opt-shift prefs reset.

Even after making new presets from the 3 default tips, the locks still work in tandem like this. So it’s not that my presets are corrupted.

Is this actually a feature that people use (how?) and not a bug?