Unable to create nodes with namespace in MaterialX Graph Editor

Tried in MaterialX 1.38.8.

Steps to reproduce:
1 - Unzip and put the attached nodedefs file in your libraries.
2 - Start materiaX Graph Editor
3 - Press Tab to bring up list of nodes
4 - from the "namespace_debug" group, select "nodedef_without_namespace"
5 - A node is created in the work area (correct)
6 - from the same group now select "test:ND_nodedef_with_namespace"
7 - Node is not created

This is a very simplified test file, but it reproduces what I see with all the nodedefs I have that use namespace.

[namespace_debug.zip](https://github.com/AcademySoftwareFoundation/MaterialX/files/14171020/namespace_debug.zip)

Please check also the video below. The video highlights 2 issues, see the last part where this problem is shown.

https://github.com/user-attachments/assets/d7ac5dd1-4ef7-40a2-b041-37a4496e5aa6

Start by reproducing the issue in the MaterialX Graph Editor with the attached namespace_debug.zip nodedefs file, following the numbered steps and checking the linked video. Trace the Tab node-selection path for the namespaced test:ND_nodedef_with_namespace entry and confirm that it creates a node like nodedef_without_namespace.

Written by the indexing model from the issue text.