Reed switch only triggers with scope probe connected
You're reed switch will pull your enable pin high when closed, but will float the pin when open.
When you connect the scope probe, this acts like a large (1MOhm) pull-down resistor which will set the enable pin low when the reed switch is open. This is important as the internal pull-down resistor on the pin is disconnected when the device is enabled, so cannot be relied upon.

A simple fix is to connect a pull-down resistor, say 10k or 100k, between EN and GND. This will pull the pin low when the reed switch is open and ensure the device is shut down.