I tried it out and it worked but it's not because of it being quads. If I use the create polygon tool, then it doesn't work and if I split or cut a plane, it doesn't work. I'll just move verts and delete faces and hopefully that will work. Maybe it's something to do with using 8.5 and Vista (I still haven't installed the service pack for 8.5).

Anyway, I don't think I would have figured that out without your suggestion, so thanks a heap!