Same problem for me too.
If I'm not wrong, Facebook developers sent an email some days ago to inform that some versions of API will change.
I guess this is why it stops working.
In Joomla, when I open the module JO Facebook, I got an error : 190 Invalid OAuth access token.
By searching on the net, it seems to be related to the fact the the new API uses a new kind of code to use the token.
I guess that a some changes needs to be applied in the module by JOOMCORE.
Please, let us know if a new update is available soon.
Regards,