might consider mantising it, it might just be a bug with that particular trigger type. though id want to exclude improper setup first. i looked at one of my models and i found that the proper usage of the triggered flag is "$triggered:" with the semicolon, this is the totality of my submodel props from pcs2 for one of my missile bay doors:
$special=subsystem
$name=baydoor
$triggered:
the subsystem entry looks something like this:
$Subsystem: bdoor2,0,2
$Flags: ( "untargetable" )
$animation: triggered
$type: secondary_bank
+sub_type: 1
+delay: 0
+reverse_delay: 500
+relative_angle: 0,0,60
+velocity: 0,0,90
+acceleration: 0,0,40
+time: 1000
only thing different for you should be type and subtype. another possibility is a glitch in the timing math caused by certain values.