Zana Mission: "Kill Invasion Boss" - Invasion boss didn't spawn

Hiya!

Okay, I've looked around and can't find another bug report similar to mine, so I'll give as much info as possible just for your info. I'm not too concerned by it, I realise how complex this game is and no doubt there will be bugs! So here goes:

I was in an Underground River Map and I got a random Zana spawn. The map I chose from Zana was a rare Arachnid Nest map and the mission was to Kill the invasion boss in the time limit. I was able to get around the entire map, including the map boss within the time limit and without dying, but I couldn't find the Incursion boss.

The Map did have a Syndicate Laboratory, however, and I wasn't able to get into the Lab before the timer finished. But when I did go in, there wasn't an Invasion boss in there. I'm not sure if the Invasion Boss despawns if the timer runs out? I've had other missions where the mobs don't despawn when the timer runs out, they just don't count towards the mission...

If it's not a bug, nevermind, but if it is I thought the more info you have the better. So, the bug report ref is: 1,556,026,438.