I do not think it has anything to do with you being a silver. It seems to me like when you engaged, it sent you into an instance that was already completed. If there is a 30 minute cooldown and you are queued up after that, then it seems there is a glitch causing the instance to not reset.
This is something that happens way too often, even in alerts where it puts you into a game that's already finished. Also there are way too many fleet actions that don't give you credit for finishing objectives which can keep you from getting credit for finishing the entire mission. It seems to me that nobody played these things for a reason, and if they were going to try and force you into playing them they should have gone through and fixed the problems first.
the last time i logged on i tried SB24 and had the exact same thing happen to me. Join in, and before the thing even starts i get a notice saying that i'm going to be removed. no exploitation or anything and it just kicks me out. Again, with such an obvious push to get more players into the fleet event's they really should have given them a pass first and made them a little better.
It's an annoyance... I can easily hit the dil cap every other day with FA daily combo, and the only thing stopping me is the kick out bug... I guess I have to wait until the next patch, hopefully they will fix it. On a side note, this is a good way to further nerf dilithium farming.
STO is the best game ever and the players love it.