The plants turn into the GRAY with no reason in the endless mode

I don’t know why that the replanted version is like that.With so many bugs that make the experience of players even worse.There’s so many images error (especially the newspaper zombie) I’m  VERY care about if my formation is neat in the endless mode.But after I made a lot of efforts to keep my formation looks neat,I saved the game and when I came in again some of the plants in my formation got into the grey color and looks really bad.Hope you guys could fix it as soon as possible.I had seen that there are some other players  had reported this bug.Plus, I want that after fixing the bug, the plants which had turned into grey in my formation could turn back into their original color, I don’t want to spend another several hours to build it up.