One vertex removed issue

we are having an issue with ExplodeAtUnweldedEdges with some meshes. In our tool we generate meshes for editing the UV coordinate, similar to what happens in the UV editor in Rhino. We therefore manipulate the mesh and then write back the texture coords to the original object.

The issue we are having is that when using ExplodeAtUnweldedEdges the mesh that is returned has one vertex less than the original one (hence triggering exceptions and inconsistencies within the tool). I have a simple reproducer that I am attaching to the topic, simply execute the python script on the given file. The input mesh as 1127 vertices and the result 1126.

Mesh_ExplodeIssue.3dm (58.3 KB) (285 Bytes)

Am I doing something wrong? Thanks a lot,