MIDI Learn Issue with JS Plugins

[Klangfarben]

So, I'm using the JS Volume Adjustment plugin and have midi learned the Volume Adjustment parameter to a MIDI CC. However, the midi cc control is not in any way linear and I'm trying to figure out why. It also seems to be that way for all the other Volume/Trim JS plugins.

Right now, I've got the volume min at -138dB (basically inf) and the max at +12dB. A midi CC value of 0 does move the fader to -138 and a midi cc value of 127 does move the fader to +12dB.

However, it is in no way linear. At all. A midi CC value of 64 always = 0 for some reason. No matter what. So, if I'm trying to emulate the throw of the Reaper track volume it seems I can't do it with a learned midi cc as values 0-63 covers a range from -138 to 0dB and values 64-127 cover a MUCH smaller range of 0dB to 12dB. The only way I can seem to get something resembling a linear response is if 0dB is right in the middle of the min/max values. For example, -12dB to 12dB. Anything else is not even remotely linear.

What am I missing here? Shouldn't a parameter that is midi learned have a linear response from 0 to 127? I'm a little confused because I don't understand why you would want it to be anything but that. Can a linear response be coded in the JS plugin itself? Or is midi learn for JS volume control sort of broken?