Please check if the issue pernrs are saved by some specific user id. The issue may be related to security roles for a particular user as when you are editing IT0008, it is getting picked up.
Alternatively, try using FM 'RP_ANSAL_FROM_PERNR' as below:
call function 'RP_ANSAL_FROM_PERNR'
EXPORTING
f_date = pa0008-begda
f_pernr = pernr "pernr value
IMPORTING
f_ansal = lv_ansal "annual salary
EXCEPTIONS
internal_error = 1
error_read_0001 = 2
error_read_0008 = 3
error_at_indirect_evaluation = 4
currency_conversion_error = 5
others = 6.