Copy and Paste in 2x Windows Explorer Share does not work.

Hey everyone,
i have a strange issue and im not shure what it's cause is, but i suspect it's a combination of 2x + GPO.
When i connect (via 2x Client) to a Desktop, copy / paste does work (on the server itself).
If i publish a windows explorer only and try to copy something from the "server windows explorer" to "my local desktop" with copy paste, it doesnt work.
it installed a ton of RAS and i did not have this issue so far.i always had the possibility to do this.
so i think the issue is some gpo that is preventing this.
i searched threw all of the gpo's on the RDS but i can't figure out which one it is, that prevents users from copy pasting from server to the local machine.

thanks for your help