Update the bit rate caused encoded bitstream lost while asyncdepth is 2

Hi, Experts

I found an issue, but I am not sure it is Media SDK issue or my application issue:

If I set encoder async depth to 2, and then let the encoder work, it works well. Assumption, the encoder output one NAL with frame number N, I update the bit rate of encoder by SDK API reset,  and then put one new frame to encoder encode function, the encode function will return NEED_MORE_DATA warning. Then I put the second new frame to encoder, it output one new nal. But this nal frame number is N+2, the N+1 nal is lost?

Where is N+1 NAL? When I update the bitrate with API reset, will the encoder discard the N+1 frame? Is there any other API to update the bitrate without   discard the frame?

Thanks

Bai