i'm sure this has been mentioned before. All enemy enemies don't react to our shots anymore (they don't shield or dodge).
I think it's caused the fix for companion metaknights shielding against player bullets. And i'm willing to bet that the devs "fixed" that bug by making all all computer controlled characters (including monsters) oblivious to any player bullets (a rather stupid way of "fixing" things if you ask me). At the moment, things are way too easy; please fix this.
Not all enemies. Only mechaknights. And if you would bother to search forum before blindly rampaging in here and posting yet another topic about this problem you would noticed it was already posted here and even devs have confirmed that its a bug and will be fixed with next update.