Spectral gaps for inactive frames for 24.4kbps stereo with DTX on with characterization item

Basic info

• Float reference: 20250917_Characterization_RC06_basop_ivas-float-update
• Fixed point: 20250917_Characterization_RC06_basop_main

Bug description

For inactive frames, most likely while DTX/CNG is active there are large spectral gaps mostly for frequency range 5-8kHz as can be seen below:

Issue is not there for the respective float condition:

In some segments there are additional gaps in lower frequency bands:

It should be noted that this a decoder issue.

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\ivas-basop-issue-2041

./IVAS_dec STEREO 48 20ms_aligned_files_concatenated.ivas.192 20ms_aligned_files_concatenated.ivas.wav