Ah, that Android file system permissions annoyance.
Here is an illustration, with the Selector Size at 100 to make it small to give more room for the brush slot icons.
This shows the difference between a palette size of 380px (the current slider minimum value) and a palette size of 270px (by editing kritarc):
As you can see, at 270px, there is a small amount of cropping along the left edge and the top edge. That’s just cosmetic and doesn’t affect functionality.
I’d suggest that you make a formal bug report for this because the current minimum slider value can give problems for tablets, as you’ve demonstrated.
Pinging @sh-zam for advice and opinion.