Hi,
Maybe a little late.......
I asume flash is installed on the servers.
It seems that citrix does not read the farm-setting correctly. All our servers were configured to use farm setting concerning speed-screen and flash settings, but they simply ignored it.
So we disabled the "Use Farm settings for Speedscreen Browser acceleration" and explicitly allowed flash-use for every server.
then enable the "Use Farm settings for Speedscreen Browser acceleration" and it works for us.
Greetz