Very odd texture issue

Sometimes when I load my WIP map this sign for example, looks like this

But other times when I load the map it looks like this, which is the desired result


Why is this happening and how can I fix it?

 

I do not see any errors relating to textures...

 

:/

Well if it sometimes works then it means the game knows where to look for the texture, it just doesn't seem to want to at times.

 

I've noticed something interesting: Whenever that sign face does not appear, neither do some other textures on my map, including the wood texture these powerlines

But when one of them work all of them work