SD1297 should not present for Trial Phase Response "NOT APPLICABLE"

I have checked the latest SDTM Terminology 2024-03-29 for codelist "Trial Phase Response" (codelist code is C66737), and this codelist indeed have a submission value of "NOT APPLICABLE" with code of C48660 as you can see from the attached screenshot.

While in our study, when we assign the TSVAL="NOT APPLICABLE"  and TSVALCD="C48660" for TSPARMCD="TPHASE", there is a Pinnacle 21 issue SD1297 for this record said that TSVAL is populated with a value from the ISO 21090 null flavor codelist. Please note that this is NOT null falvor but the CDISC Submission Value in SDTM Terminology.

So could you please kindly provide the explanation for this issue so that we can add this explanation to csdrg since we believe it is correct to assign the TSVAL="NOT APPLICABLE"  and TSVALCD="C48660" for TSPARMCD="TPHASE" rather than move the value to TSVALNF. Thank you!