COMPLETE EXPLANATION (Read below to see a note, the steps and results):
I always use the spacebar to move the canvas with the pan tool, and I keep it hold while pressing "ctrl" to zoom in and out, and when I release "ctrl" it appears back the pan tool hand, because I kept the spacebar hold. But in this 4.4.2 version of Krita, after switching from the pan tool to the zoom tool several times, there is a time when the hand of the pan tool no longer shows up, and I can't move the canvas anymore, even without having released the spacebar. This only happens while moving the cursor with the pen of my Huion Inspiroy h1161 tablet. Because if I do this process while moving the cursor with my regular mouse (of if I don't move the cursor at all), zoom and pan tools swich perfectly. And that's a problem, because I need to move the tablet pen constantly to move the canvas and zoom. 
It seems like Krita automatically unholds the spacebar. Because, after the pan tool deactivates, it shows up the brush tool circle in where the cursor (tablet pen tip) is, and at that very time, when I press "ctrl" again, it doesn't activate back the zoom tool.


NOTE:
I have to warn you I have many customized shorcut, including the ctrl button, in which I set it to activate the eyedropper. However, the pan tool worked totally fine in the last version, even with all these customized shorcuts. 

DRAWING TABLET USED: HUION INSPIROY H1161


STEPS TO REPRODUCE
1. Hold Spacebar, so it activates pan tool (to move canvas)
2. (While 1) Press ctrl button to activate zoom tool. Release it and press it many times. 
3. (While 1 and 2) Move the pen of the (huion inspiroy) drawing tablet. 

OBSERVED RESULT
One moment it stops switching from zoom to pan, and pan tool doesn't work again, even if you hold spacebar. 

EXPECTED RESULT
Pan tool always works while you hold spacebar, even after activating many times the zoom tool. 


THANKS FOR READING AND HAVE A NICE WEEK! KEEP ON WITH YOUR AMAZING KRITA SOFTWARE!