Thanks for the possible solution but i downgraded to 4.5.10.1 and it made no difference. The bug is still present.
I cleared out my cache to ensure js files where not cached but still no luck.
Can i go back further without loosing functionality? Do you have any idea when a release with a fix will be available?.
I have 2 clients who consider their sites broken right now and i really need a fix asap.
Thanks