How to Troubleshoot USSD Menu Display Issues
If you dial the USSD number without starting with * or #, the dialer will not display the USSB menu. So please add * or # at the beginning of your USSB number depends on your mobile processor's standard.
If still can not work, please download STK, install it to the terminal.
Notice, now the firmware can not support any USSD api, so you can only use dialer to dail USSD number.