How do I get into the Fort Frolic atrium?

Note: This is about entering the Fort Frolic atrium for the first time, not about getting into the upper level, which seems to be the most prominent issue people encounter.

After Sander Cohen talked to me and sent spider splicers my way, I dispatched them. It seems that I'm supposed to go advance into the atrium now, but the doors are still closed. Cohen isn't talking anymore and there are no living spider splicers to be seen or heard. I've checked guides like this one and it doesn't seem like I should need to do anything else...

I've tried leaving the area and coming back but nothing happens. Is there something I missed?

Solution 1:

It's a glitch I believe. I fought with my back near the door and only four spider splicers jumped down. Reload and move about. You should have six spider splicers jump after you.