Go to pie chart --> format --> set the minimum size to 0.01%
As some of your values are pretty much small when compared to the others that might be a reason
sliceCollapsingThreshold number The threshold at which smaller slices should be collapsed into a consolidated slice. Valid values are between 0 (no collapsing) and 1 (all slices are collapsed into a single pie). 0.01 (slices smaller than 1% of the whole pie are collapsed)
Basically, the problem is that your other values, even all added together, are so small that they are just not significant in relation to the 440K+ counts in the two main categories -- they sum to about a half a percent, so that's only a 2 degree visual slice, divided between the nine categories.
A pie chart is just not a good way to represent those lesser categories. I haven't seen a "3-D funnel" visualization in splunk, but that might be a good way to go here, based on your data.
If you really want to put them in there, I'd suggest to either do it on a second, smaller pie chart, or add a table of their nominal values.
The alternative might be to override the name or stats of the "Other" category so as to display the whole mini-table with a mouse-hover. I'm pretty sure that can be done, although it might require quite a bit of work.