Inconsistent polygon behaviour when including CP column

[whelena]

I'm plotting single-sample SRC results using the fish-plot + tree feature. The data frame input looks like:

parent	label	length.1	CP
5	1	8	0.865
4	14	37	0.560
5	4	11	0.990
1	7	48	0.860
NA	MRCA	122	0.930

Output plot :

I think this output is because CP of node 4 is greater than MRCA. But, this is also inconsistent with different CPs

CP 4 = 0.93 ($CP4 = CP{MRCA}$)

CP 4 = 0.8

CP 4 = 0.3 ($CP_4 < CP_14$)

Here the colour ordering is changed too