Faces disappearing after saving

I have run into this problem multiple times. I build a model and then I save. After it loads to save some faces disappear. I am wondering if anyone else have ever ran into this problem. One way that I avoid this is by grouping the face that disappears and also locking it. Then when I save, it does not go away.

I am curious to see if anyone else has had this happen multiple times as well?

I had it happen in SU 2016 first and had it happen again this morning in SU 2017

I’m having this issue too

I appreciate the work around because it’s super annoying.

It is because sketchup automatically fix problems when they are found. But sometime it erase faces.

To fix the problem : General preferences > unselect “Automatically Fix Problems When They Are Found”