WP edit – wysiwyg disabled & textarea color white

Hello,

My wordpress backend have some strange bug after updated wp.
I’m now with:

- WP Version : 4.2.2
- EMG-Lite Version : 1.3.21
- Site URL : http://www.xxxxxx.xxx/site
- WP Multisite : NO
- PHP Direct Access : YES
- Memory Limit : 64 MB
- Active Theme : Twenty Twelve
- Active Plugins :
     Easy Media Gallery

Everything work fine except when i want to edit a post/page i don’t have the wysiwyg/bbcode-button showing and the text color in the textarea to edit a page/post is white.
I don’t have any js error in the browser console and the only thing that make wp showing the wysiwyg/bbcode-button is to disable your plugin.
I also have twice the settings item in the drop down when i hover “esay media gallery” on the top wp admin bar.
I have try to replace with a fresh downloaded /wp-includes, check if everything (theme inclued) is up to date, disable de concatenation of js in the wp-config, use the google library instead of the local one, check if my website address does not contain semicolon (everything i have found on internet to solve the problem).
It’s really related to this plugin.

Do you have any clue on how to solve this ?

Br,

videogramme

https://wordpress.org/plugins/easy-media-gallery/