Hi,
I had a quick look : 2 observations
as I suspected, when your max is 100, values of 100 datapointlabels are not shown, see this chart,
where i made these changes :
yAxis: { max: 115, endOnTick: false
If you don't make endOnTick false (default is true, making the max > 100 would add an extra outer spiderweb line

As for the placement of the y axis labels (red), you think they are in the wrong spot but for comparison, if you make it a simple radial again, you can see they are on the right spot then (radial distance from center point). See below, the red number are exactly on the right spot, see above, they are on the same spot, but because it's a poligon instead of round guidelines, it looks wrong. You could argue if this is a bug or a feature, I'm leaning towards bug.

One solution to this would be to show those red numbers on one of the axis, instead of between the axis, it is possible, see this example, but I haven't really figured out how to achieve this. I would think something to do with distance and tickmarkPlacement, but can't make it work.
See also this, I'm done searching for now.
Good luck with it, and if you find it, please keep us posted.
Dorine