RAW from Sony A7III

You can share a large file by uploading it to somewhere like dropbox or googledrive or onedrive and post a public share link to it in a message, here.

How do you know half your images aren't converting?  If you point the DNG Converter to a folder of ARW files and output the DNGs COPIES to the SAME FOLDER, then half the files will be DNGs and the other half will be the original ARWs that the DNGs were converted from.  The DNGs are compatible with older software but the original ARWs won't be.  The fact you've renamed the files that do open makes it difficult to tell whether the ARW files actually correspond to the renamed ones or not.

What software are you using that you need DNGs and what version?  Is this Lightroom and it is an older version so you need to convert to DNGs?  An older version of LR will only be able to open the DNG copies not the original ARWs so half the files, the DNG copies, will import and the other half, the ARW originals, won't.  Same with an older version of PS and Bridge.

The two screenshots you've shown us only prove that you have some photo files that Windows Explorer can read thumbnails from (we don't know the extension of those), and ARWs that Windows cannot read the thumbnails from.  That's about all that the screenshots show.