Mesh doesn't show in built game! (Not a material/shader issue)

I use ProBuilder a lot in my project and almost all of my meshes show properly in the built game.
However from time to time, a mesh won't show in the build of the game ( but it shows in play mode ).

The only fix I found that works is relatively simple: Just delete this mesh and make a new one (with ProBuilder again) and it will show in the build properly. However, I would like to know how to avoid doing this, and fix the mesh itself so that I can avoid doing twice the work when a mesh gets bugged..

Just to reiterate: this has nothing to do with materials/shaders.

How can I reset a ProBuilder mesh to a state where it has been newly created without losing all the vertices I created? None of the buttons in the Repair menu have worked.

 

I just had this problem occur once again:

In editor, the ground shows:


In build, the ground is gone:



In order to make the mesh appear again I must delete the probuilder mesh and recreate it from scratch.
Any ideas what's happening?