We are experiences an issue with the Flip effect in the latest version of firefox, there is no animation and the content on the flip page appears in reverse on the screen.
The issue also occurs on your demo page for the flip effect, we have seen this on multiple devices running the latest version of firefox.
As far as i can see no errors are reported and nothing shows in the console
.k-ff126 .fx-flip {
transform: rotateY(0deg) !important;
}