Merging Assets results in Gloss/Reflection

First, I don’t know much about using Unreal, I just started learning to try and make a simple render.

I have a tile of a road, and I duplicated it until it was large enough to be a street. I then wanted to save this ‘street block’ as a separate asset both for convenience and optimization, however, when I did this, the new combined asset looked nothing like separated ones and instead looks like a blue reflective plane. I’ve attached screenshots of the exact process I used.

Any help with how to make the merged asset look like the child assets would be appreciated!