Vegetation Studio output node connectors disconnect on settings changes

Following steps for VegetationStudio implementation (https://www.youtube.com/watch?v=IImkLyPcqfU) and having the following issue:

Changes to the VS output node e.g. selecting another layer and changing settings (for example ticking 'Take Terrain Normals') deselects some or all of the connectors into the VS node.

Using Unity 2017.4.2 on Win10 MapMagic 1.9.0 Vegetation Studio 1.3.1.0