Dolphin 20.12.1, okular 20.12.1 on KDE NEON.
The problem is that sometimes I want to launch okular to open PDF documents while browsing the local filesystem via dolphin, but nothing happens: no window, no error, nothjng at all.
I thought some problem were related to the document, but if I open a terminal and launch okular specifying the path the program starts immediatly.
I see this behavior especially when I do a file search and therefore I'm displaying the search result.
However, it could happen even without the search action, what I see is that once okular refuses to start (silently), it will not start anymore by dolphin.
Any idea?

Have you tried launching Dolphin through the terminal and from Dolphin, opening the PDF? Debug/error messages would reflect on the terminal.

jerixmx wrote:Have you tried launching Dolphin through the terminal and from Dolphin, opening the PDF? Debug/error messages would reflect on the terminal.

Every time I start dolphin from the command line it works, that is I'm not able to reproduce the issue.
Could it be that dolphin invoked from the UI is launched with a different type of settings? But in the icon application settings I don't see any particular option.