[C6727] DSPLIB DSPF_sp_biquad() function hangs with nx=32

I'm using C6727 DSPLIB in it's ROM equipped, when calling it's DSPF_sp_biquad()

hangs up  !  calling with nx=32 .

This limitation is not noticed with library reference.

or, is it Errata issued ?

large enough like nx=192 is well working in same testing program.