Hello!

I've discovered a bug in Abaqus 2019.HF6 (fix pack 1947). In a model for simulation some kind of additive manufacturing process one may use layer-by-layer adding of material alternating with partial machining (i.e. partial removing) of the previous layer. This can be done by using tricky mesh and multiple model change interactions (explore the model generated by attached Python script for more details). While viewing results one can observe disappearing of some element faces in such model on intermediate solution steps (see picture in the attachment).

Steps to reproduce the bug:

1. Rename element_faces_disappearing_bug.txt to element_faces_disappearing_bug.py (sorry, it's not possible to attach a *.py file here).
   
2. Run the Python script element_faces_disappearing_bug.py to create the model.
   
3. Run Job-1 and view results after the job completes.
   
4. Go through the solution steps and watch disappeared element faces.
   

The bug has been found in Abaqus 2019.HF6 (fix pack 1947).
OS version: Windows 10 Pro 1803, 64-bit.

Best regards,
Mikhail Kozlov