GameObjects going grey as they move away from the camera

Very new here, reasonably new to Unity, not so new to game development.
Have spent the day trying to understand what is happening and finally think it’s time to ask the experts!
I am experimenting with some helicopter models in a scene in SteamVR/Vive. When they are close to the camera they display perfectly, if I move them roughly 100 away (up) from the camera they start to grey out, the higher they go the less detail, very quickly they look like solid flat 2D light grey sprites.
From my development days I’d assume this is because there is a fog layer, nope. The LOD’s are messed up, nope there aren’t any. The MipMaps? nope turned them off in textures->advanced.
Skybox? Nope does it even against a plain background. So I’ve switched things off and on, messed with shaders, filter mode, etc. etc.
I’m at a loss what to try next.
Any suggestions? sorry if this is a duplicate I’ve spent the day on google and forums and best I found was disable MipMaps but no better.


Thanks for the reply, I have a normal camera in the scene as well, and if I switch it on and the VR camera off yes it’s exactly the same.
But I also have a completely new project, it has a small amount of objects in the scene and has the standard Unity skybox, if I place the same helicopter in the scene and do exactly the same raising it upwards it stays ‘good’ all the way up until it’s a small dot.
I should add I have a light attached to the helicopter (as a child) below it, a spot shining up so I don’t believe it’ll be a lighting issue but could be, struggling to think how to be 100% sure.