Film "unavailable" - Manjaro Linux

When I click on a couple of films in my library I get the "Unavailable" red button. Clicking on one of these films I get the following

/Data/Films/Carol.2015.mp4 < and >/mnt/Data/Films/Carol.2015.mp4<

My films are on a separate disk which is mounted on boot. File listing on /Data/Films/ is as follows

┌─(chris) > {/Data/Films}
└──┤ ls
'Florence.Foster.Jenkins.2016.avi
'Alice in Wonderland.avi'*
'American Gangster.avi'*
'American Graffiti.avi'*
'Bill Bailey'\''s Remarkable Guide To The Orchestra .avi'*
black-swan-.avi*
'Blade.Runner-Director'\''s.Cut.avi'*
'Blazing Saddles .avi'*
'Brdget Jones The Edge Of Reason.avi'*
'Bridget Jones The Edge Of Reason.avi'*
'Brokeback.Mountain[2005].avi'*
Bruno.avi*
'Burn After Reading.mp4'*
Carol.2015.mp4

Can anyone offer an explanation as to why this is happening? - and more particularly how i fix this so my wife can watch these films.