ZXDS Custom Keyboard Config Help

I'm trying to set up a custom key configuration for Atic Atac on my New 2DS XL. In the custom/readme.txt file it says you can create a custom config for each game and put it in the custom/keyboards folder, with the same name as the snapshot or tape image file. When you load the game in it should then use the matching config file from this folder.

I have an Atic Atac.z80 file in the ZXDS/Data folder, and in the custom/keyboards folder I've created an Atic Atac.cfg file with the following contents:

# ZXDS custom keyboard and button config for Atic Atac.

Up = Up
Down = Down
Left = Left
Right = Right
A = Fire
B = Shift
X = 0
Y = Caps
L = QUICK_LOAD
R = QUICK_SAVE

# EOF #

Which means the control stick and A button are mapped to the Kempston joystick, B is mapped to Symbol Shift, X is mapped to the zero key, etc.

However, when I load Atic Atac.z80 up, not all the above match. Everything is fine apart form the last two options. The left shoulder button is mapped to the Caps Shift key, and the right shoulder is mapped to Symbol Shift, instead of Quick load/Quick Save.

Any ideas?