So strange on the pretrigger.
I have mine set for 15secs and I get weird numbers for DS analysis, but I do get them all, regardless of the set timing(500ms/750ms/1sec)
for example with 1 sec I get:
t-533
t+1
t+934
t+1934
t+2934
etc
and, the 'first frame', t+1 in this example always has a...