Can not set qland on FBWA for failsafe

I want my Flying Wing aircraft to switch from FBWA mode to QLANDE in a possible failsafe situation, but no matter how I try, it switches to QRTL mode.
please help

What have you set in the Q_OPTIONS bit mask? You may have bit 5 or 20 selected.

https://ardupilot.org/plane/docs/parameters.html#q-options-quadplane-options

No, we dont use 5 and 20 bite. We prefer default setting for Q_OPTIONS. So it means we use 0 bite. We would be very greaful if you have any other recommendation about our problem.