Yikes, that must have been a nasty shock first thing in the morning!
2 of the mugs look like the liner glaze is okay, how and what did you use there? or am I just not seeing the flakes there?
Having this happen with 4 different glazes is odd unless it is the same base with different colourants. Since some of the work only had 1 coat it wouldn't seem like thickness would be the cause. Did you thoroughly mix up the glaze in the jar before applying it?