this happened about a week ago to my newest pirate and 3 times since last year so in your case a old add on in mine recurring over excessive agro with invisibility and endless unseen attackers that isnt the norm on kings and if not a glitch then its not normal.over level 25 this may indeed be a blast to work thru for level 22 and under its no more than a death trap without a fast reacting crew to help flee lol big difference in a similar situation
at one point i and 1 other tried to fight 8 when another player ran to us with more on them a good guess would be 15 -25 actively attacking then turn run disappear and resume attacks , a few could be found with ranged dagger by the red cursor if we scanned but most remained out of sight to respond to and the damage became unmanageable. a side note that once it started all player regen also stopped only potions and doll returned health. very very nasty combo of effects.
now i could totally have no issue to the agro if they remained visible to react to but when multiple are striking from beyond its not fun or correct play. and this "glitch" continues to this day at kings and sometimes inside all forts with passing thru walls and from upper level when attack a lower level soldier also remains inconsistent, they can move like ghosts and we cant, disappear we cant, keep attacking with no retaliation back. if intended to work in this manner then perhaps still a bad decision. it adds only confusion and frustration to players, not a challenge worthy of the game. and it remains uncorrected as it resurfaces again and again randomly and to varied extreme.
not unlike the endless quest dig failure recently ,again rampant among players (check forum for thread for the vocal few , and multiple bumps to get attention to address, and speculate how wide spread it may be) that for those that looting alone isnt the purpose of play ,and like questing is equally annoying and apparently also never resolved for a solution -other than keep trying and eventually it might clear , 31 days and still counting on same pirate above(i retry each bugged dig mission daily fyi, 4 separate missions all stuck at dig ) is the longest to date to still not get past. this leads to early level players having added stress to play and advance, that true ,high level players are no longer concerned by(having got past it) everything is easy at 50(or when you fully understand the games mechanics, to maximize effects) at lower level and less play obsessive newer players not so much, careful what we ask for, and add to the game , as the level and severity it impacts all players and level of play skill varies. lest we change , challenge or just out right kill the fun right out of it. thankfully its still beta and as long as aware the chance of it being adjusted always remains at least a hope