Are these custom 3do's? What do they look like up close in winmip/your image editor?
Even though you have pointed out in the distance the pink I am seeing it appears in the 3do's up close as well if you look very carefully:
Another common mistake with transparent mips is when you select the pink to be transparent your texture cannot have
any semi-transparent pixels or the pink will register very easily in sandbox/the game.
For example take this shape I have on a pink background, looks good right?
Well... not exactly becasue if we were to go into winmip2 and choose the pink as the transparent texture we would still get that 'halo' pink effect around our object. If we zoom in closely to the edge of our texture you will see the edges have many pixels that are semi-transparent:
Every pixel on your texture need to be fully opaque. There are several ways to make a texture in a paint program output full pixel opacity. In affinity photo (what quick method I use) it has a very easy tool to select different pixel opacity levels and isolate those for editing. In this case I need to remove/make the semi-transparent pixels fully opaque so I choose this option:
After I create a alpha layer of my texture that only includes the full pixel I just mask it to my texture and boom:
You can see here very up close no pixels have the pink 'bleed-through' which appears to be the issue your textures might be having. Now when I go back to winmip2 and select the pink both in sandbox and in-game I will no longer see any pink pixelation artifacts surrounding my 3do objects.