Using 'Expert RAW' app on new phone to take DNG's, they are displaying as thumbnails in the lister and viewer pane but when viewing in the standalone viewer this message appears.
here is sample photo
sample.zip (7.4 MB)
I have the same effect here.
I do not use any Adobe photo related programs.
The Adobe DNG Codec is still available from third parties, but not from Adobe AFAIK.
That will open a DNG in the Windows Photo Viewer, but not in the Directory Opus stand alone viewer.
The Adobe DNG converter is still available from Adobe, but it only converts to DNG, not from.
This is a Win 10 Point of View.
My upgrade to Win 11 has yet to be done. 
Edit Note: Your Moon is upside down in Australia
How high is the moon in the sky ?
Good point - need metadata field for angle above horizon, pretty sure the sensors can do that. As to your question about 45 degrees, using optical zoom x5 on the phone, so normal height.
I am only a few miles North of the 45th Latitude parallel.
The moon's actual latitude is a topic beyond this discussion.
But certainly, near the equator, the moon is much higher than here .
For me it is not displaying in anything.
Directory Opus 13.16.2 (Beta) Build 9293 x64
OS 6.1 (B:7601 P:2 T:1) SP 1.0 "Service Pack 1"
IrfanView 4.72 displays it; 4.70 did not.
I'm also experiencing this issue. Here's some photos for testing. All taken just now, on a Galaxy S24 Ultra. Two using ExpertRAW 4.0.05.0, freshly installed, and one from the native Samsung Camera app, version 15.0.02.36. The huge idiot responsible for messing up my exposure in the third shot has been sacked.
Only the Samsung Camera app's RAW opens in the Opus viewer (SamsungCamera.dng).
All three generate thumbnails in the lister.
All three are viewable in Windows Photos.
ExpertRAWExamples.zip (58.1 MB)
Sounds like this format has only recently been supported by LibRaw. If so, Opus should gain support when we next update the library.
So I can expect a patch later this week right? 
Jokes; good to hear!
I have the same issue - but with DNG files from different photo software. I will look for improvement after next (non-beta) update.