Okay, so I've got two cups that seem to work the best for me; both are medium Melunas, but one is the soft version, and the other is the classic. My period started today, and I grabbed the soft one since I'm expecting to be rather active today. Not gonna happen, my body isn't accepting the soft one today, it leaked like crazy. The Classic is working fine today though.
This seems to happen to me pretty often. Sometimes one cup just refuses to work right, even though both of them generally work perfectly for me. I guess things in my body are just situated differently some days?