I have Okular configured that when it's already running and I open a pdf from the command line, it should open the new file as a new tab in Okular.
However, if this new file is in another directory than the other one, Okular fails to open the document and only displays an empty tab with the file name and the error message
Could not open /path/to/bar.pdf
okular foo.pdf & okular bar.pdf
works the way I would expect it to.
okular foo.pdf & cd .. okular foobar.pdf
would only open foo.pdf correctly, but fail to display foobar.pdf.
The Okular version I'm working with is 0.19.3.
//Edit: Maybe I should mention: If I open the same combination of files from a file manager (in my case Dolphin), Okular behaves as expected. I only have issues using the command line.
//Edit: I just tried the same thing on another computer using Okular 0.23.2. It worked fine, so I guess the bug has been taken care of already.