Please help. CC disappearing when placed.

I know this is a common issue but I am having an uncommon problem. 

I have gradually deleted every mod to try and rectify this issue but when I place my newly made item, it disappears. This seems to be particularly related to when I place the item and the cursor then highlights something else immediately, eg putting a coffee table on a rug, if the cursor is not over that coffee table when I place it and is actually over the rug, the rug will be immediately highlighted on placing and the table disappears. 

I have removed every item of CC. I have updated TS4 Studio. I have deleted my entire Sims 4 folder in my documents, deleting all my saved data in the process. Sims 4 itself is up to date. I have remade the coffee table in the most updated TS4 Studio. I have not edited any scripts or anything, it’s just a new mesh for a coffee table. And I am STILL having this issue. Please help me. 

side note on a personal level. I am currently having lots of drama in my life, and 3D design is something I love and is bringing me joy and purpose. So without this I am just so bored and miserable. Please help me 😔

EDIT: SOLVED!!!!! qolygonal posted the solution below.

My specular map was too small. But I bet it had a great personality!