I. think i found the solution... I managed to call the SQF and SQS from the misison folder directly, I didn't put it in a effects folder. It works in preview and it works with launch from pbo file. All is needed is to test if the other players online will see the dust.
As it was before either we saw no dust anyone, or we saw only the front dust if I launched by preview mode(as if Circle.sqf wasn't read ?!?)........ So here attached is the new DUST SHOCK as I see it COULD work in MPmisions. I ONLY changed the INIT line to read the sqf in misison folder direclty,
and so you must call the AddEventHandler as follow :this addEventHandler["fired",{(_this + ["Gun120"]) exec "shock_dust.sqs"}]
(instead of \effects\shock_dust.sqs")
Using a EFFECTS folder seems to bug the pbo compression or not get accounted for, get attached file and look, I also manually added the grass color dust to be more dense (not as much as sand), SO IF I COME BACK TO YOU IN 24H OR LESS TO TELL IT WORKED WELL FOR ALL ONLINE, YOU WILL HAVE TO MAKE IT V1,1 AND USE IT LIKE I CHANGED IT. This way it won't work only for preview mode or SP play. ;D