This webpage (documentation.microfocus.com/.../index.jsp) suggested there could something wrong with the FD, so I cleaned up the indexed file FD and received the same results as above.
FD IN-FILE
LABEL RECORD IS STANDARD
DATA RECORD IS IN-RECORD
record contains 8 characters.
01 IN-RECORD.
02 IN-KEY.
03 FILLER PIC X(3).
03 FILLER PIC 9(3).
02 FILLER PIC 9(2).