I was with a group of 5. We had just finished Dark Forest II and III loaded. I gave a message I would be busy for a minute. When I came back from busy status after about 1 minute, I started walking and saw no enemies. I thought perhaps the group, who was still near me, had killed them all when I was gone. However, I then noticed that the rest of the group was fighting. I got close to them, saw no enemies but they were definitely in combat. I tried auto-attack to see if I could auto select the enemies. No go.
After about 10 seconds, an enemy appeared in front of me and then as I panned around the enemies were there.
I thought it was maybe something with a slow connection, however my ping was 67 and I was on high speed cable internet.
I wish I had taken a screen shot but the 10 seconds went by fast.
I was playing on my iPhone 3GS.