Too many of Proteus 0.6 with F767 are behaving strangely in terms of SWD programming. Maybe we have a hardware design issue? Maybe we are missing something?
3) make sure you have "STM32 BOOTLOADER" driver not "STM Device in DFU Mode". If necessary update/install driver from C:\Program Files\STMicroelectronics\STM32Cube\STM32CubeProgrammer\Drivers\DFU_Driver
4) Enter cmd.exe, enter C:\Program Files\STMicroelectronics\STM32Cube\STM32CubeProgrammer\bin folder
3) make sure you have "STM32 BOOTLOADER" driver not "STM Device in DFU Mode". If necessary update/install driver from C:\Program Files\STMicroelectronics\STM32Cube\STM32CubeProgrammer\Drivers\DFU_Driver
5) close STM32CubeProgrammer, unplug USB cable, plug USB cable, open STM32CubeProgrammer. STM32CubeProgrammer is finicky you really have to restart it between steps