Multiple lines appearing and dividing face after saving file

Hello all,

Something odd is happening to my Sketchup file. I have a building modeled that on one singular face random lines are appearing and dividing that face into multiple smaller faces after saving the file. Using Ctrl+Z or erasing all the lines create the original face again.

I uploaded the 30sec video showing this happening:

Any ideas on how to fix this? I can upload the SketchUp file if anyone wants to take a deeper look into it.

Thank you,

Please upload the file!