Redmine

when i for instance create a ticket and want to do a copy paste
then the past within the ticket description does only work with the context menue (right mouse butten and paste)

here is my configuration of my current environment of my redmine version:
Environment:
Redmine version 3.1.1.stable
Ruby version 2.0.0-p647 (2015-08-18) [x86_64-linux]
Rails version 4.2.4
Environment production
Database adapter Mysql2

and here is my firefox version: 51.0.1 (32-Bit)

it seems that this issue startet with someone last update of the firefox?!

if i try chrome browser this copy paste works fine!