MFA signon fails with the following for users that have a missing/blank MFA segment:
10.15.36 STC83586 CCSR010E SAFRT00E S0C4 at 331463A2 LMOD SAFRT00E CSECT SAFRT00E +00178A MFAMAIN N/A MFAMAIN
16.22.36 STC83586 CCSR010E SAFRT00E S0C4 at 331463A2 LMOD SAFRT00E CSECT SAFRT00E +00178A MFAMAIN N/A MFAMAIN
01.02.00 STC83586 ---- THURSDAY, 02 FEB 2023 ----
14.27.59 STC83586 CCSR010E SAFRT00E S0C4 at 331463A2 LMOD SAFRT00E CSECT SAFRT00E +00178A MFAMAIN N/A MFAMAIN
20230201162236.472384 STCMAIN:AZF2105I Authentication request (PC)
20230201162236.472409 STCMAIN:MFAA Version=4, MFAA Length=296, Application=TPXABCD , STC UserID=ABCD
20230201162236.472413 STCMAIN:Derived Name= , Session Type=6
20230201162236.472416 STCMAIN:Password length=8, New password length=0, Claim=N/A
20230201162236.483928 STCMAIN:AZF2205E Auth eval failed (R_Factor error), sts:0, safrc:8, racfrc:8, racfrsn:0x4
20230201162236.483935 STCMAIN:AZF2211E Auth preparation failed, cannot evaluate
20230201162236.484018 STCMAIN:PC return code=0x8, reason code=0x1, abend code=0x0
Release : 16.0
Deleting the acid and rebuilding it with a valid MFA segment causes S0C4 to go away.