If I use the File Search to search for file content, the application gets stuck at some point and does not do anything. The green progress bar will keep going. Checking Windows Task manager, one can see that CPU and IO activity is very low suggesting nothing is happening.
This is a known issue with Windows' preinstalled PDF file handler in combination with certain PDF files.
In order to be able to read the content of certain files, our software uses file handlers that are registered in Windows. Unfortunately, there seems to be an issue with Microsoft's PDF file handler, which causes this behavior in rare cases.
The same technology is also used by Windows' File Explorer (you could reproduce this issue in File Explorer as well). What you can do as a workaround is to install a different, third party file handler for PDF files, such as the one from Adobe.