It may be that there are actually some stuff outside the orange border that is not easily seen.
Zoom in closely and look at your image and add a color fill layer below so you can see it more clearly.
You may need to use the Crop Tool instead of Trim.
I will use the Crop Tool in this case, but I need to get the Trim Tool working. I know there is no clutter because I used the Rectangular Marquee Tool to make sure there were no light pixels causing a problem. The border is clean. In the meantime, the Trim Tool is not responding.
Are you sure there are no stray pixels out there. Two stray pixels could cause a borders like you show. Below I created a document with a transparent border. I dupe it and in the duped document I added two stray pixel at 1% opacity. You can not see them but their there. I then used menu Image>trim on both documents see the results.
Thanks for taking time in such detail to help me with my problem. I agree with you that there might be stray pixels too difficult for me to see because the absence of any behavior by the tool would indicated that to be the case. What tells me it might be something else is the way the Trim feature has not responded for several weeks on a multitude of objects. It is strange for sure. Tomorrow I will share the image in question with Tech Support at Adobe. If they can complete the trim, I will know something is askew. Thanks again!