How does the meshjoin work?Why it failed?

I made a icosahedron base model using Gh+Wb.

But in the last step, the meshjoin failed random. Some points didn't weld correctly.

So I bake the mesh, using Tspline tsweld and tsthick ,it successed.

I don't know why the meshjoin command failed random. What can i do to avoid the situation ?

32m.gh