Options from external commands in vim?

If I run from the vim terminal

:! zathura foo.pdf

It opens foo on top of the terminal and when I exit I go back to the vim file. If instead I try:

:! zathura --fork foo.pdf

The intended behaviour is to open the pdf in a new window while still having the vim file open. It doesn’t open at all. What do I do to fix this and why is it occuring?

:! st zathura food.pdf