I just updated from mediawiki 1.26 to mediawiki 1.27 (including all extensions), and since then, the MsUpload-bar won't show up.
The MsUpload-Extension is shown as istalled in Special:Version .
However, if I try to edit an article, the MsUpload-bar won't show up. It is just not there.
Apache and php do not throw any error...