Directional Lighting lights wrong side of objects

So here’s my problem. There’s a column model I use extensively in my scene. It’s a blueprint. Shadow casting is fine, but for some reason, the directional lighting strikes some columns from the wrong side:

Same columns from the other side:


Also, there are instances where the columns are lit from the right angle, but shouldn’t be lit at all, as they stand in the shade:

Any help would be greatly appreciated!