Reproduce:
1) Load any datanode (US4DCyl)
2) Select in statistics
3) Delete it
4) Load another node (Pic3D)
5) Select in statistics
= Histogram still shows the deleted node but not the new one, update can be triggered by checking "Show subchart"
Also interesting: If you have a ROI selected for the second node than "Show subchart" will show you the histograms: US4DCyl[0], US4DCyl[0] with Circle1, Pic3D with Circle1 (although you never asked for the US4DCyl and the node does not exist in the storage anymore)