I was a passenger on a friend's ship, hunting Ki-Rin with him in the Mooshu skyways. Every time we got into a fight with them I was frozen out of the first round of the battle. My pirate and crew were visible, as were the enemies, but we were all stationary to me while he got his first battle board. Once he locked in his actions I could watch them play out but do nothing.

Once the second round started the battle worked normally for both of us, but I (the passenger) was locked out of the first round of every Ki-Rin battle we did.

I have the same problem, me and my friend were in cool ranch and we were on my ship, my friend will go in battle with me but she will zoom in on an ally and/or friend. I can see her and her companions on the board and on her screen it will zoom in and show an enemy or ally. If I choose my moves and press done, It waits until time runs out. The only way to avoid it is for rafts, to be at the back on the board. On skiffs to be up were the driver is, or on the steps in the front. (Generally any where the battle field isn't) and then join in without being pulled onto the battle field. However it will show my characters fight and all there animations and stuff. Otherwise I really love the game. This bug does need to be fixed tho.

Cunning Andrew Jellico level 26 Swashbuckler

This will be partially fixed in an upcoming update (There is a bug that affects passengers who are aggro'd when an enemy spawns on top of them). However, passengers will still need to manually aggro enemies on the ship deck when you are hunting a "flock" mob, such as Ki-Rin.

Also, as a note, if you are grouped together, this shouldn't be a problem if you are in Broadside combat and your ship is boarded, in this case you should be automatically pulled into combat.