I’ve had this problem many times over a few years but I don’t know how to avoid it. When I take a certain random action (it’s different each time) suddenly this will happen on a face near to the one I’m working on. This time it happened due to deleting a line on a face that wasn’t even adjacent. The lines appear hidden at first, but upon selecting ‘unhide all’ the lines appear, which have broken up the face into many smaller triangular faces. These smaller faces obviously cannot be treated as one, so I’m often faced with the pain-staking task of deleting each new line one at a time.
Does anyone know why this is happening and how I can stop it?