Is there a way to stop Sprites from clipping, becoming invisible against background?

Hi, I have a 2d sprite in a 3d scene, and when I am a certain distance from it, the sprite becomes invisible against the background and when I approach, the sprite can suddenly be seen against the background. Any advice or insight would be great.
I would like it to stay visible against the background, if this is possible.
Hopefully the screenshots help explain what I mean.

 

that floor also has same sprite shader material? (with transparency)

 

Well done, thanks for your help, that worked. There was some transparency on the floor. I feel so nutty trying to consider the possibly hundreds of aspects of the game.
Anyway, peace.