Okay I’m back.
I’ve spent all day recreating my road and sidewalk. I’ve imported the new piece into Unreal Engine 5.32, and the lines ARE BACK! But after some cloning, I realized that you were right. It was the lighting.
This is what a copy of the object looks away from the scene:
This is a screenshot of the area with an additional diagonal light:
THE LINES ARE GONE!!! o__0
I should have known since I’ve made this project in version 4.26 in 2018. I’ll fiddle with the lighting later as I have a token to exploit now. I’ll fill you in later with the results.