After 19 years, I finally found the REAL cause of the “Curtains Down” 1 witness glitch
When you go into the upper level where you plant the bomb on the Chandler for a accident kill there is a women in red sitting in the lobby of the opera there is Also a hole in the ground near the Chandler if you go into it you can see where the ambassador falls and trips and you detonate the bomb to kill him
the women would somehow see you from there and if not the reason the 1 witnesses has to do something with upper level in the visible hole near the Chandler because the only time I got 0 witnesses
Was not going in it just above it and doing the accident kill if you like to disprove or recreate it be my guest.