Synthesis sometimes missing when switching from TCX_10 to TCX_20

At 48 kbps stereo, with the following bitstream, the synthesis is sometime missing when switching from TCX_10 to TCX_20.

ltv_STEREO_32k_-stereo_48000_32.zip

As shown above, it happens at frame 2876 but also at least at frame 4166.

On the figure, in order from top to bottom:

• Left channel floating point
• Right channel floating point
• Left channel fixed point
• Right channel fixed point
• Left channel float and fixed point difference
• Right channel float and fixed point difference
• Core left channel
• Core right channel

decoder command line :

IVAS_dec STEREO 32 bit syn

this has been observed with 40400bd0

tagging @fotopoulou and @kiene