Sankey: not all flows are presented

[Zoophobus]

In some cases when using the Sankey diagrams the flows presented between the activities are not visible within the main window/screen, despite some flows being presented in the "map/overview".

Part of this issue might be related to performance related issues with the display, this issue arose from a user with limited hardware. (Wider issues regarding to the usability of the sankey diagram from users with less powerful hardware have also been reported).