OK, obscure discovery in retail fred.
If you have a given number of ships....say 6.....and according to the mission objective all must have been destroyed, or destroyed or departed in order to complete the objective, you cannot have any of them self destruct.
ie.....your main objective is to clear all enemy ships from the area. we will say that there are 3 cruisers and 2 corvettes. You are in a bomber.
the mission objective looks like this right?
>true
which becomes:
>is destroyed delay
>>0
>>ship 1
>>ship 2
>>ship 3
>>ship 4
>>ship 5
or for destroyed or departed:
>is destroyed or departed delay
>>0
>>ship 1
>>ship 2
>>ship 3
>>ship 4
>>ship 5
ok here's the thing.....while refining the mission, you decide to add a cruiser and either have it self destruct when the mission begins, by using a sexp in the events editor, or have it self destruct 1 second prior to mission start. Do not add this ship to objective sexp. The sexp won't work if you do. Also on this line, if you have a message sexp set up in the events editor that cues off of the ships being destroyed, or departed or destroyed....it also will fail if you add a ship that self destructs by either method. This will also not work if you set it as a departure cue for the ships....
>percent ships destroyed
>>66
>>ship 1
>>ship 2
>>ship 3
>>ship 4
>>ship 5
>>ship 6 (which is set to self destruct in either manner)
Trust me on this. I don't know if it still happens in SCP, but it is obscure enough that it just may.
