You can switch between each development environment, but each time you will need to put your board into download mode first and then flashing the respective firmware you require onto the board.
That is the correct behaviour. On the ESP32, MicroPython presents itself as a serial port, not as a mounted USB drive. The mounted drive only happens when using CircuitPython on your board.
There is a known issue where the firmware is copied and then the board reboots itself before your OS thinks the file has completed copying.
There are several tools you can use to access the MicroPython REPL and copy code to your board.