Flash and shutter speed

The synchronization speed of flash is 1/200s. If you set the shutter faster and pop up the flash, the speed will automatically drop to1/200 s.

You said that using the shutter of H7 1/4000s is the high-speed synchronization of the flash. Generally, you can set high-speed synchronization with professional flashlights such as Canon's 580 EX II and Nikon's SB900.

There is nothing wrong with the camera and your operation. Generally, the built-in set-top flash of SLR cameras is asynchronous at high speed.