Hello,
Since PL 9.6, the export does not preserve the metadatas.
In the export dialog, I select Include All, and tick-in every possible choices (Exif, Attributes, IPTC etc), however the exported DNG does not have any of the attributes populated (Camera info, Author, rating, keyword - everything in blank)
Issue seems to show only when exporting to compressed DNG.
I tested on both Windows 11 & Mac Tahoe 26.3.1 - Same issue
I checked a group of images I processed yesterday with 9.6: All the metadata that was in the original RAW file (NEF) and sidecar (XMP) is in my exported JPGs. However, after seeing your post I went back and exported to DNG (compressed): Description and keywords (hierarchical and flat) were missing! Location data (coordinates, country/state/city/location) was present in the DNG along with rating, creator, etc. See attached ExifTool data dump.
As @Stuck recommends, you should report this to DxO.