Windows 10 has a messaging system. You obstruct that with sleep(33). In this case use Application.ProcessMessages instead of the silly sleep, which is blocking.
You will be OK unless you access the clipboard in nano seconds..
You have to give the OS the time to process its message queue. Sleep() is not a very bright idea.... Although under Windows with one! exception: Sleep(0) has special meaning and means relinquish time slice. Any other sleep is bad programming in such a scenario, even sleep(1)....