SUMMARY
The wacom pen button 1 always uses the pan tool to pan around the canvas regardless of the modifiers I change in Wacom Tablet Properties and/or inside Krita Canvas Input Settings.  I'd like the button 1 (closest to the tip) to be the button to change brush size, this is possible in CSP and PS(CS6).
I briefly managed to make it work when removing Krita inside the Wacom Tablet Properties application list and using the "All Other" application settings, but after I re-opened Krita the functionality got lost and the pan tool was default again and no amount of settings and input switching brought back the brush size change functionality.

STEPS TO REPRODUCE
1. Have a Wacom Intuos (not pro) M Bluetooth (connected with the USB cable)
2. Krita in its default settings
3. Assign shift + Left click or just Shift in Wacom Tablet Properties to the pen button closest to the tip and try to change brush size inside Krita.

OBSERVED RESULT
The "shift + left click" uses the pan tool instead. Changing this setting to anything else will also result to Krita using the pan tool. The "move hand" logo appears and moves around the canvas. Not changing to the actual tool. The same functionality as pressing down on space bar and left click holding and moving the mouse.

EXPECTED RESULT
Shift + Left click as per in Krita's default settings should change the brush size with the wacom pen but does not.