Can't paint walls

Hi

When I am trying to paint walls, I hover over the wall with the wallpaper selected and the wallpaper shows up on the wall. When I click to apply the wallpaper, the wallpaper disappears for a moment but then reappears. When I press 'cancel' to remove the wallpaper from the mouse selection, the wallpaper removes on the wall. Sometimes the wallpaper removes after I click the mouse to apply the wallpaper. 

And then when I went to save this version of my game, I click on save as and it just loads for ages and doesn't come up with my save files. 

When I pressed 'exit' to exit the game without saving, the menu went away and it went back into live mode, as if I'd never pressed exit.

I'm on windows PC, I don't use mods or CC and my game was working fine on 28/09 (today is 30/ 09) and I moved house without issues on the 28th. This is my first time on the forums so please let me know if I need to add any other information.

EDIT: I repaired my game and it happened when I restarted the game