Not sure why, but it happened to me coming from Durban last month. SA/LX to AMS, then UA to SFO. Would only check bags to AMS. I assume it is because The LX flight from JNB did not have TSA approved security. SA to IAD does, so no problem with it when I go that way. Haven't been through SIN for about a year, and it still seems easier than my last trip.

Now here's the next question. Doing another return from DUR on 11 Jul. Will route SA to JNB, thne LH to LHR, then UA to SFO. I assume I will have to collect bags and clear customs and recheck with TSO approved security at LHR. Might be close. Arrive LHR at 0805 and depart at 1005, switching from LH to UA. Not sure how this will go with the new terminal change. Shoudda thought of this sooner. Maybe I'll switch to a later flight. Will need to check soon since it is a Z fare on UA. Might sell out.