On my wacom pro pen and art pen I have the button furthest from the tip set to SPACE key. When I press the button the hand appears but pan/scroll does not happen. Pan/scroll DOES work with the EK remote's lower middle button, which is set to SPACE by default.
This is a really old bug but I cannot find hte other report. However, why don't you set the back button to "middle mouse click" because that defaults to panning in Krita as well? https://docs.krita.org/Navigation
*** Bug 393691 has been marked as a duplicate of this bug. ***
Hi, Clint! Sorry for long response. The bug is now fixed in the current nightly builds! It will be release in Krita 4.2. And right now you can test the feature in the testing builds from here: https://binary-factory.kde.org/job/Krita_Nightly_Windows_Build/