[regression] Encoder crash for McMASA 7.1+4 16kHz input at 64kbps in convertToBwMS_fx()

Basic info

• Float reference:
  • Encoder (float):
  • Decoder (float):
• Fixed point:
  • Encoder (fixed): 99e792d1
  • Decoder (fixed):

Bug description

The fixed point encoder crashes with an assert:

Assertion failed: (0), function L_add, file basop32.c, line 1661.

Ways to reproduce

Box folder: ...\Box_EXTERNAL_IVAS_BASOP_VERIFICATION\issues\issue-1505

./IVAS_cod_fx -mc 7_1_4 -max_band WB 64000 16 bm3aa1s05_16.wav bit
# this crash also occurs for 5.1+4 am3aa1s13_16.wav at 48 kbps