Ethernaut, I went back and did a bit of experimenting. I found that the type of program that I used to create my models has some influence. For example, I made my models in Paint3D. But, I got the impression that Microsoft don’t like obj; as oddly, the obj format doesn’t exist in Microsoft’s 3d Paint unlike most programs and anything made with Microsoft’s Paint 3D and converted to obj doesn’t work well in ANY program I tried.
This was unlike Tinkercad where I made my model. After making my model in Tinkercad (virtually the same model), I downloaded it in obj format and converted it to .b3d using Fragmotion and I didn’t get the remnant and it worked perfectly. So, I think it goes back to the program that I used. I will keep experimenting to confirm this.