error when modifying a copy of a template in backend : Invalid Token

Hello
Since I use the last versions of Flexicontent (3.3.1) and Joomla! (3.6.4), I always have the same message when I modify the copy of a template in backend-administrator : message "Invalid Token".
This message (Invalid Token) appears even if I just try to save a copy of an original Template without change anything !
But when I try to save an original Template without copy (default or blog or faq or items-tabs or presentation), no problem, no error message.
How to modify a copy of a Template, please ?

Hello

could it be a problem with the new "template" name which is also a folder in the disk

can you try with new template name "mytest" ?

Hello
No there isn't any problem with the name of the new "Template" copied and saved. When I try with the name "mytest" for exemple, it is the same : I can't save modifications on the file item.php in backend (Template menu) and there is always the same message "invalid token", even if I try to save without changing anything.
I rectify what I wrote on my last message : This problem appears when I try to modify the original Template too (default, blog, faq, items-tab, or presentation).
I remember I didn't have this problem with oder versions (FLEXIcontent v3.0.13 or V3.0.12 for exemple).
Luckily, the modification of the file item.php works corectly when modifying directly on the host (without Flexi menu).
So it doesn't matter !

Hello

you may send me a PM with super admin access to review this