"Search" does not find all photos regarding keyword

On macOS, v10.15.6, I have thousands of photos sorted in directories by year (2001, 2002, 2003, …) with subdirectories (based on days).

I selected the overall directory for indexing within DxO PhotoLab 3.3.2. After indexing was finished I tried to search photos by keyword. It shows me only photos until 2007 (JPEGs, DNGs, TIFs). But all photos later than 2007 (RAW with XMP files) are not shown or maybe not found.

Do I miss a specific option for searching?

Thanks in advance for any tips/hints.