Hi Andrew,
Thanks for pointing out the line of code. It seems like calling multiple times of JRoute::_() causing EasyBlog router failed to build the sef link at backend
Anyway, we manage to fixed the issue
Attached the updated router.php, can you download this router.php and copy the file to folder 'JOOMLA/administrator/components/com_easyblog/includes/' and overwrite the existing 'router.php'. Remember to backup the original router.php file first before you overwrite with the updated version.
This file should fix your sef issue when autoposting to facebook from EasyBlog backend
The same fix will be added into next release of EasyBlog
Hope this help and have a nice day!