Occasionally when I do modeling, this one trouble "cancer-like" face will suddenly show up and ruined everything, if I delete that one particular face, it will appear in another one, until I delete the whole model. I'd like to what caused this to happen and is there a way to fix it for good? Thank you!
The way to get rid of cancer is by removing the bad cells. I can't say what is causing this bizarre behavior, but it does look like you are modeling with smooth mesh preview enabled. Typically you don't want to model with that turned on, only use it to preview. One quick check you can do to make sure you don't have…
Thanks Alex! Yeah this bad cell only occurred when I smooth preview mesh, and when I check cleanup mesh, that cell is completely normal (4-sides, no any lamina face and no nonmanifold geometry). That's why I just undo workflow and now it's not there. However, the unknown cause of its appearance sometimes still weird me out