Simulacrum - bug

I am still a bit perplexed on what happened. I started a new wave, and accidently clicked on a portal. When I came back, I was standing outside the event area. I was able to kill a few of the mobs through the gate and ultimately finished the wave. The gates however still did not open for me to continue the event. Bummer. I was nearly complete and it took me quite sometime to collect the splinters.

Is this done intentionally to keep you from attacking things outside of the event? If so, why not disable portals to be used altogether? I am trying to determine if the lockout is intentional.

Thanks in advance!