Comparing the variables IND and CLASSWK of Indonesian data between 1980 to 2010,

I realized the number of observation for NIU(not in universe) is perfectly aligned EXCEPT FOR 2010:

IDN(2010) [https://international.ipums.org/international-action/variables/ID2010A_0435#codes_section]

CLASSWK [https://international.ipums.org/international-action/variables/CLASSWK#codes_section]

Since IDN and CLASSWK assume the same universe and CLASSWK is from a follow-up question of IDN, the exceptional discrepancy in 2010 does not seem very intuitive.

Can I know why there is such a difference only in the 2010 sample?