possible bug in Unity 5.4.0b17 - 2d side scroller

New to Unity and a 3d beginner. i'm creating a 2d platformer prototype on a deadline and successfully imported sprites. they have all turned solid magenta in the scene and game previewer (assets are fine in the assets window). i can redo the environment by placing all the assets again and they render fine, but then turn magenta...if i select each magenta sprite in the scene and hit reset in the sprite renderer - they return to their correct state but not for long and the game display is now empty and doesn't preview the scene. Also, as I work, sprites keep turning magenta. if i reset all sprites and save, all sprites turn magenta. I believe this is a bug, it is persistent and repeatable.

sprites are .png's for transparency I need a permanent fix. please explain solutions step-by-step/carefully. just in case it's hardware: I have a Mac: processor: 3.5 GHz Intel Core i5 memory: 32 GB 1600 MHz DDR3 graphics: AMD Radeon R9 M290X 2048 MB thank you for any help - using free version. I hope I'm using this forum correctly. apologies if i am not

 

I've had this issue due to the default Sprite shader disappearing from the Sprite renderers. Putting it back in fixed the problem for me permanently, but I would think resetting it would do the same...

 

Putting sprites back in has not helped...did you re-import sprites or just replace in the scene? Replacing in the scene doesn't work for long and the game preview is not working at all. i thought i would rebuild a new project

 

I was just talking about the shader, not the actual sprite. When it turns pink it means that Unity isn't recognizing a shader for it.

 

OH. OK. not sure how to do that. how do you replace/put it back in? BTW: thank you very much for responding =)

 

In the Material section of the Sprite Renderer component, make sure it says Sprites-Default (or whatever material you want to use there). This seems to go missing at times for some reason.