I am using Teensy 4.0. Arduino 1.8.13 and the latest Teensy uploader. I uploaded many times a sketch which compiles and uploads but Arduino IDE always stays in hid#vid16c0&pid 0478 bootloader (teensy 4.0) in the ports menu and never resets and if I unplug the usb and re plug in then its not recognized and have to keep pressing the onboard reset button until it is, tried many different usb cables, if I go and upload a simple sketch like blink then the board will reset and the Teensy board with port number will reappear, a few others who are also doing the same project using the same IDE version, same code had no problems, they even sent me the HEX file and that uploaded through loader then the board reset without problem, I did disable anti virus to see if that would make a difference but none, there must be something missing, wrong setting somewhere. but I am thinking it is with IDE and not Teensy loader. I have deleted everything, reinstalled several times, I t did used to work but no idea why suddenly it does not.