SSL VPN connect via RDP - Freezes when playing video

Hello,

Running fortios 6.4.4 on a FG61E. When connecting through SSL VPN and the portal by RDP to a Windows host everything works at first. However when I start for instance a youtube video on the host (or a video starts by itself on a website), it freezes and becomes unresponsive. I have to make a SSH connection to the host and kill the browser/youtube tasks to make the host responsive again.

In the release notes it states that this (long standing) issues should have been fixed. It isn't.