Update:
It is happening more frequent and now it involves on more accounts at once. This only happens in combat. Randomly many of my characters seems to be going to Link Dead but it doesn't. I see the mob's health going down, I can swap targets. However the screen won't update. For instance I just did the Xegony fight, and those affected won't see the adds past the first wave, and Xegony is standing there with 0% health. I will post some screenshot to try to explain what it looks like.
Below I have attached two screenshot of my current game play. The affected were more than those. Today it happened on Plane of Tactics twice, Plane of Air 1 time (Xegony Fight).

- Necro Affected.
- Affected Character (Necro).jpg (197.02 KiB) Viewed 518 times
If you can see that the necro is still on 100% connection, with Xegony standing and 1st wave of adds still alive. However in reality the fight is over. Its like the game is waiting to be updated but not gone Link dead. The only fix IF you haven't clicked or casted anything is by camping or force quitting with /exit. (or in some very rare case, it fast forwards to the state it really is).

- Monk Not affected.
- Non affected character (mnk).jpg (224.77 KiB) Viewed 518 times
This is how the current state should look like on all clients.
On plane of tactics out of 15 characters 9 got affected. 2 on main pc and 7 on 2nd pc. On Xegony 4 got affected. 1 on main pc (the tank) and 3 on 2nd pc (bst, Necro, Ench). Its very random and its quite frustrating when it happens. I am not sure what is causing this, and this only started to happen a few days ago. I haven't changed anything on my PC nor configuration of the game.
P.S. My god image is gigantic... sorry about that. Also Should have told what client I am using and such. Using UF client, on PC using MQ2 from MQemulator (standard, not gold) and running with WinEQ2. On 2nd PC I am just using same MQ2 as PC1, but without WinEQ2.
This only happens on combat and not right at the start. Usually when you have pulled and few seconds has passed. I notice it when I see pets going through the mob toward where ever they are heading and the mob animation stops playing. For normal batch of mobs its not much of an issue, since I can still target them and send commands "IF" I have not used click items or casted a spell, since when I do have used a clicky then it spams with "you cannot do that command right now..." In that case /camp won't work so I have to /exit.