you are the third user that have this problem.
I’ve seen some screenshots of other users, and it seems that the page is not fully loading, because style isn’t applied and “Update” button is not visible.
Probably apache exit with an error, can you send me a tail of its log?
Finally I have fixed the issue.
The problem wasn’t wordpress but php, because the plugin use the function “bin2hex” that is available only for PHP >= 5.4.
I have replace with native mysql function.
Update the plugin to the 0.9.13