I asked this question already and got zero useful responses. Trying again. (Note: I'm new to Blender. Before I commit a lot of time to trying to learn how to use it, I'd like to be reassured that it can be a suitable replacement for my previous modeler. It won't be that much use to me if it can't carry out this import operation. It seems like it should be easy -- but I can't get it to work!)
Personally, I think it's a bug in Blender. However, I was just at the bug report page and it seems that they assume any newbie who can't carry out this operation is just too dumb to know how to do it correctly and refer them back to this page. So here I am. (They might be right. Nevertheless I have reason to believe that Blender is NOT importing the data, which makes it a bug in my book.)
For example, I can import the same 3 .obj files into Cheetah3d and the objects appear as expected. To me that means there's nothing inherently wrong with the obj files I'm trying to import. So why doesn't it seem to work in Blender?
There was a suggestion that the imported objects may not appear because they are either too small or too large, or because they were located off center. The first two .obj files certainly contained objects that might have been too large (they still didn't appear even when I zoomed out or in). So I created a third object scaled at a only few feet in the originating modeler, assuming that would make scaling issues less of a problem. That one does not appear in Blender either, but works just fine in Cheetah3d. So all three of the files open fine in Cheetah3d but when I try to open them in Blender they don't appear.
I was also told I should check on the "dimensions" of the object I imported, but I'm such a newbie I can't find where Blender provides that information. I've seen a tutorial that indicates that it should be in the same spot as the "location," "rotation," and "scale" information, but it is not. Not on my system. It's been moved, apparently. Where, I can't figure out.
Another thing: the first two .obj files contain multiple objects. When I import either of the files into Cheetah3d, I see a list of the names of the component objects. In Blender, the only thing I see is the name of the .obj file. That also suggests (to me at least) that the data in the file is NOT being imported. It's not a problem of scale or dimensions. Blender isn't reading the data. Isn't that a bug?
When I say nothing gets imported, I mean I see nothing in the 3d view or the top, front, and right views. In the Outliner, I see the name of the imported object next to a sort of orange upside down triangle. If I click the arrow symbol, a greenish-blue triangle appears underneath bearing the same name. If I open one of the files containing multiple objects in Cheetah3d, I see a list of the parts in the Objects window. In Blender, all I see in the Outliner are the two upside down triangles bearing the same name. Under Properties, it gives the origin as 0, 0, 0.
Is this really not a bug? I am still very new to Blender. If I am doing something wrong, I wish someone would tell me. Or is this a bug in Blender?
MacOS Montery (12.1) / iMac (Retina 5K, 27-inch, 2019) / 3.6 GHz 8-Core Intel Core i9 Blender 2.93.6