ID 251790 - Missing data error when exporting an incorrect layer

Problem summary
A 'missing data' error message sometimes appears when exporting an incorrect layer created by custom nodes within Session Scripts

Customer reported version
3.2v1
Customer reported platform
Cross-Platform

Steps to reproduce

1) Create a New Project

2) Insert a Node (for example a Grade) in between the paint node and the merge node 'Base'.

3) Notice the base paint layer changes to a procedural layer in the Layer Stack palette.

4) When you export a session, that procedural layer is then flagged as 'Missing Data' which is simply Mari telling you that the layer is strange.

Workaround
Unknown.

Reproduced by support
Win 7, OS X
3.2v1

Expected behaviour
The node graph should be able to export the custom node with no error message.

Actual behaviour
The following error message displays:

'There are custom entities in this project that have missing data which is required when importing'