I'm trying to make a very simple object in Blender and export it to Unity. The object is a simple square that has a glowing (neon-style-like) rim (or frame). What I did was adding square, inserting faces to create an inner square. Then I separated the planes (inner square and outer frame) to assing different materials to them. Then I assinged a material with red color and red emission to the frame (all I can think of to make it look neon-style) and just some black color material to the inner squre. I selected both objects and exported as .fbx, then imported in Unity. But when I add this object to scene, it is invisible. What did I do wrong?
[I'm very new to Unity and really used Blender for the first time]