Perspective (?) problem

I have a lot of tiles, on top of which towers are placed.
When hovering the towers range is shown: A flat cylinder (part of the tile) becomes visible under the tile, just above the floor. However this "feature" can only be seen on the tiles in the middle of the game-window (?!?).

When moving the floor up/down the "area of visibility" changes - even if the floor (flat cube) is always below.
(Moving the camera also affects it but not enough...)

See the difference between Game- and Scene-windows:

There IS a red cylinder under ALL the tiles
- What's happening ?!?

 

Perhaps it is part of your prefab or even debug drawing. Regardless, Unity won't do that unless you somehow, or something you're using causes it.

 

OK, I found the culprit - The floor material's shader was set to "Sprites/Default".
Setting it to "Standard" made the problem go away . So that's .. hmm...