Check the Pages tab in the config app. I believe it is enabled by default. It's possible your Fences accidentally got moved to another page.
This is probably what happened. A few years ago all of mine vanished for "no reason". After reading all the information in the Fences help, I realized they probably vanished because I was on another page. I "grabbed" the left side of the screen and moved it to the right. Everything moved back to where they belonged. Having multiple pages can be very handy once you know they can exist.
