When you press F1 to close the menu it puts the focus back on the game but keeps the visual UI on your screen, so then you have to press F1 again to get the cursor back and close the menu
Thank you for your help in alerting us to this bug, now that all of the required information has been gathered, it's been logged with the development team who will look to fix this.
Thread locked, awaiting development team response
Excellent news! This has now been fixed by the development team and will be released in a future server update.
Thanks for doing your bit to help us keep the servers bug free!