Installed the latest 4.4 full release and I can still only upload zero to four photos at a time before it fails with the "Photo upload failed, but no error string was returned from Facebook" message. And now with 4.4 officially released, it looks like we're going to have to wait several months before we have any chance of seeing this one fixed.
FWIW, all the usual "solutions" I see on other forums were tried. The facebook app was deleted and re-granted permissions, permissions were manually changed to "Everyone", browser was closed so no other connections to facebook, etc.
The log file the plugin allows me to save simply contains the following useless information:
Plug-in error log for plug-in at: C:\Program Files\Adobe\Adobe Photoshop Lightroom 4.4\Facebook.lrplugin
**** Error 1
This plug-in’s post-processing task did not finish successfully.
Could not get album info from Facebook.
**** Error 2
This plug-in’s post-processing task did not finish successfully.
Photo upload failed, but no error string was returned from Facebook.
**** Error 3
This plug-in’s post-processing task did not finish successfully.
Photo upload failed, but no error string was returned from Facebook.
**** Error 4
This plug-in’s post-processing task did not finish successfully.
Photo upload failed, but no error string was returned from Facebook.