CC2340R5: DIO21 connected to GND does not work

Part Number: CC2340R5

Tool/software:

Hi,

I am using basic_ble project, after burning hex it works fine, but after connecting DIO21 to GND and resetting it doesn't work, what is the reason for this.

sdk:simplelink_lowpower_f3_sdk_8_10_01_02

Using a TI development board