Existing files not imported

Audirvana 3.5.33, macOS 10.14, files on external HD: Audirvana does not import certain files. In iTunes and Yate these files do not differ from the rest of the files of this album and are well recognized. I already checked integrity of A´s library: is OK.
Playing the whole album by opening the files with A functions: The missing files are played but not imported.
The play queue shows the following abnormality:

Are there any propositions for solving that?
Thank you

Hard to tell as there are many reasons why this happens. Do you have a cue sheet in the directory? Do you have “strange” characters in the file names of tracks not imported? Did you manage to have all the tracks recognised and played by A when dragged and dropped to the playing list directly?

Thank you @patifr for your feedback.
There is no cue sheet.
not recognised by A: 1-09 Brandenburg Concerto No. 3 in G major, BWV 1048 - 2. Adagio
recognised by A: 1-08 Brandenburg Concerto No. 3 in G major, BWV 1048 - 1. Allegro
No real difference with regard to the used characteres in the file name.
A is capable to play the not recognised tracks too.
There must be a difference between these files, but I can’t identify it.
One difference is, that A is not capable to read most of the ID3 tags of the not recognised tracks as can be seen in my screenshot. iTunes and Yate are able to read the ID3 tags.
When I reencode these .aiff files with XLD again to an .aiff file, A can recognise the files.

Adding these “new” files to a playlist was not possible, because not “recognised”. Deleting the last character of the file name made it possible. The file stayed in the playlist after readding the last character. So there seems to be a problem for A managing its library.

OK, I see. It appears there are kind of invalid characters in the file name of some tracks. I cannot count how many hours I spent chasing for those appearing to be “wronlgy encoded” characters. They appeared as normal on displays but were not. But in my case, this was due to the use of network share with the nice SMB thing.
If you cannot manage to put a file in a playlist without making changes to the file name, you will have to update the file names.
Now, on my side, to avoid any further problem of that kind, I’m forced to perform a complete check before trying to import new album. I drag and drop the directory to the A playlist and see if tracks are recognised. If yes, then I know I can put everything in the Audio folders.
Thing is that in the absence of import logs you do not know what is really happening. I’m not even sure that all my audio files have been imported…