It is not possible to use the Create StaticMesh button to create a Static Mesh from a Procedural Mesh with only 3 verts. The following if check is the reason:
if (RawMesh.VertexPositions.Num() > 3 && RawMesh.WedgeIndices.Num() > 3)
This if check should be checking for >= 3 instead of just > 3.
Note: If this is intended functionality, it may be useful to add a warning/error message for when this is attempted.
Regression?: No
This also occurs in 4.14.
Head over to the existing Questions & Answers thread and let us know what's up.
| 0 | 
| Component | OLD - Anim | 
|---|---|
| Affects Versions | 4.14, 4.15, 4.16 | 
| Target Fix | 4.16 | 
| Fix Commit | 3344782 | 
|---|---|
| Main Commit | 3362661 | 
| Created | Feb 23, 2017 | 
|---|---|
| Resolved | Mar 14, 2017 | 
| Updated | Apr 27, 2018 |