Hey there,
This can be possible only in two cases
(a) When the width and height are not set. In the screenshot,
(b) when you have added the custom CSS to hide these buttons. It could be possible in your case.
it is also possible you have applied custom css and does not provide a class name.
Like this: http://prntscr.com/kwhk85
Refer: http://prntscr.com/kwhjkb
If still it will not work then paste this custom CSS in wp-admin > Appearance > Customize > custom CSS
.single-course .certificate_generated .extra_buttons {display:inline-block !important;}
Let me know if it resolves.