I found a way to do this.
Find the file in the normal file explorer. Note which folder it’s in.
Go back into spaces. Create a new space. Call it junk or deleteme, or something to note you don’t need this forever.
The new junk space should be synced with the folder containing your file of interest.
Go into the new junk space. Click and drag the little 2x3 array of dots that appears to the left of a note when you hover. This is the same thing you click and drag to reorder the notes inside a space.
Click and drag the file from your junk space to the space you want to see it in.
Last, clean up by deleting the junk space. When you delete a space, it does not delete any files.
Any file can appear in multiple spaces.
Developers of plugins are not always writers, so there are gaps.
My “favorite” documentation glitch is the widely quoted example of creating a list of all files with the dataview plugin (straight quotes used instead of back ticks to keep from confusing forum formatting):
Of course, that won’t work. The proper syntax is:
Don’t see the difference?
The first, non-working, example uses “LIST”. The second, working, example uses "LIST " with a space following the word LIST.
Obsidian is great, as are the community plugins. Polish would help, though, at least in some areas. I say that as an enthusiastic friend, not meaning anything negative.