I am sure this is not a bug but a problem from my side, but i am posting it here to ask you guys about it:
I recently updated to firefox 49.0.2 and since that update i have a weird problem on the "Manage Covers" upload part.
The button "Select Files" does not show anymore... the others works fine but this one will disappear after the complete load of the page.
I am pretty sure there's a problem with Java...
I currently don't have Java installed nor any Java module for firefox.
I don't explain why it worked before and not now anymore.
Ideas ?