Go to your fences configuration.
Check the Desktop Pages section
See if "Switch Pages with Alt+Left / Alt+Right, or Alt+MouseWheel" is selected.
Hold the fence you want to move to a new Desktop Page. (check if you are actually moving it)
Press Alt+left (seeing that is the "issue side").
You should now be holding the Fence you wanted to move on the Desktop Page you wanted to move it to.
Hope this helps you without moving the taskbar itself.