I've had this issue with this same gun before but thought it was fixed. Not so apparently.
Went to the range today and was having issues with the trigger not resetting when shooting suppressed.
It's a 10.5" Noveske with a M4-2K and a Geissele S3G. Without the suppressor the gun runs fine. Once I attached the M4-2K it will occasionally fire fine, eject, and chamber another round but the trigger won't be reset. I have to pull the charging handle back just enough to reset the trigger and then it'll fire again. This happened probably 3 or 4 times out of 100 rounds.
I thought maybe the gun was short stroking or something (not sure how it'd be short stroking but picking up a new round) so I loaded up a mag with 1 round and fired; it cycled and locked back just fine.
I'm thinking this is just something I'm doing wrong; poor trigger control with the S3G. I say this because I tried experimenting with how I was squeezing the trigger and if I sort of lightly pulled, just enough pressure to fire, but still following through, I'd get the above issue. If I pulled the trigger with some authority I never had the problem.
So if it's just me, what's happening mechanically that the firearm completely cycles but the trigger isn't reset?