Mouse Over Inconsistency

I've been trying to use the MouseOver function on several objects in my scene, but it is acting very inconsistently. The MouseOver action does not seem to be registering when the cursor is on the upper half of the game objects. Oddly enough, it only registers when the cursor is on the bottom portion of a game object. This has been happening with all game objects that use a mouse over event.

I'm using a capsule collider for some of them, and a box collider for others. Doesn't seem to be much difference between the two in terms of how the cursor interacts. I've been experiencing this problem for quite some time now, and I would really appreciate any tips/advice that anybody could provide!! Thank you.