Canvas change position and not render correct on ios

Hello everyone,

I got a problem such as the title. My panel manager will close previous panel when jump to the next panel. All panel has a canvas and stay in a same layer. This layer also has a canvas component. I close the panel by setting the position of it. I just want to reduce the rebuild and render of canvases by this way.

Everything is working in editor. But when I build to ios, setting the position of previous panel will result in the next panel disappear. I log the position of previous and next panel, it seems that there is nothing wrong. The strangest thing is that the ui elements such as buttons and toggles in next panel all can click, Ijust can't see the panel. I guess there must be something that i don't know with canvas. Anyone can help me?

unity version 5.2.3p3

canvas render mode screen space-camera