In earlier version (I think 5.1.0) LO on Windows showed ligatures in OpenType fonts… in 5.1.3 this behavior disappeared again.
Ligatures in the few Graphite fonts do work as expected.
Thank you for filing the bug. Please send us a sample document, as this makes it easier for us to verify the bug.
I have set the bug's status to 'NEEDINFO', so please do change it back to 'UNCONFIRMED' once you have attached a document.
(Please note that the attachment will be public, remove any sensitive information before attaching it.)
How can I eliminate confidential data from a sample document?
*** This bug has been marked as a duplicate of bug 66916 ***